assignment 5 sem

8/12/2019 Assignment 5 Sem

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iii) Testing of Algorithms

Ans. The ultimate test of an algorithms is that the programs based on the algorithm should run

satisfactorily. Testing a program really involves two phases a)debugging and b)profiling.

Debugging is the process of executing programs with sample data sets to determine if the results obtained

are satisfactory. When unsatisfactory results are generated, suitable changes are made in the program to

get the desired results. On the other hand, profiling or performance measurement is the process ofexecuting a correct program on different data sets to measure the time and space that it takes to compute

the results.

Q.3 What is a linear data structure ? Give examples. Describe how an array is represented.

Ans. A data Structure in which every data element has got exactly two neighbors or two adjacent

elements except two elements having exactly one data element is called a linear data structure.

Array is a finite ordered list of data elements of same type. In order to create an array it required to

reserve adequate number of memory locations. The allocated memory should be contiguous in nature. The

size of the array is finite and fixed up as a constant. Some of the important operations related to arrays are,

Creation() – A[n], Array created(reservation of adequate number of memory locations) memory reserved;

Write(A,i,e) – Updated array with ‘e’ at ith

position;

Compare(I,j,Relational operator) – Boolean;

Read(A,i) – ‘e’ element at ith position;

Search(A,e) – Boolean;

Q.4 Write algorithms to implement the following operations on a stack - create, push, pop.

Ans :

Algorithm: Create

Output: S,Stack created

Method :

Declare S[SIZE] //Array of size=SIZE

Declare and Initialize T=0 //Top Printer to remember the number of elements

Algorithm ends.

Algorithm: Push



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Input : (1) S, stack; (2) e, element to be inserted; (3) SIZE, size of the stack(4) T, the top pointer

Output: (1) S, updated; (2) T, updated

Method:

If(Isfull(S)) then

Print(‘Stack overflow’)

Else

T=T+1;

S[T]=e

If end

Algorithm ends

Algorithm: Pop

Input: (1) S, stack;

Output: (1) S, updated; (2) T, updated; (3) ’e’, element popped

Method:

If(Isempty(S)) then

Print(‘stack is empty’)

Else

e=S[T]

T=T-1;

If end

Algorithm ends

Q.5 What is a first-in-first-out data structure ? Write algorithms to perform the following operations on

it – create, insertion, deletion, for testing overflow and empty conditions.



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Ans. A queue is an ordered list in which all insertions take place at one end called the rear end, while all

deletions take place at the other end called the front end. Queue is a linear data structure which works

based on the strategy first-in-first out(FIFO).

Algorithm: Create

Output: Q, Queue created

Method:

Declare Q[SIZE] //Array with size=SIZE

Declare and Initialize F=0,R=0

// Front and Rear pointers to keep track of the front element and the rear element respectively

Algorithm ends

Algorithm: Isempty

Input: Q, Queue

Output: Boolean

Method:

If(F==0)

Return(yes)

Else

Return(no)

If end

Algorithm ends

Algorithm: Isfull

Input: Q, Queue

Output: Boolean

Method:



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If(R==SIZE)

Return(yes)

Else

Return(no)

If end

Algorithm ends

Algorithm: Insertion

Input: (1) Q, Queue; (2)e, element to be inserted; (3)SIZE, size of the Queue;(4)F, the front pointer; (5) R,

the rear pointer

Output: (1) Q, updated; (2) F, updated; (3) R,updated

Method:

If(Isfull(Q)) then

Print(‘overflow’)

Else

R=R+1;

Q[R]=e

If(F==0)

F=1;

If end

Algorithm ends

Algorithm: Deletion

Input: (1) Q, Queue; (2)SIZE, size of the Queue;(3)F, the front pointer; (4) R, the rear pointer

Output: (1) Q, updated; (2) F, updated; (3) R,updated; (4)e, element if deleted;

Method:

If(Isempty(Q)) then



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Print(‘queue is empty’)

Else

e=Q[F]

If(F==R)

F=R=0;

Else

F=F+1;

If end

If end

Algorithm ends

Q.6 What is a graph ? What are the two ways of representing a graph ? Describe with the help of

illustrative examples.

Ans. A graph G=(V,E) consists of a set of objects V={v1 ,v2,. . . .} called vertices, and another set E={e1,e2 . . . }

whose elements are called edges. Each edge ek in E is identified with an unordered pair(v i ,v j ) of vertices.

The vertices vi ,v j associated with edge ek are called the end vertices of ek.

The most common representation of graph is by means of a diagram, in which the vertices are represented

as points and each edge as a line segment joining its end vertices.

A graph that has neither self-loop nor parallel edges are called a simple graph, otherwise it is called general

graph. It should also be noted that, in drawing a graph, it is immaterial whether the lines are drawn

straight or curved, long or short: what is important is the incidence between the edges and vertices.

In the Fig. edge e1 , having some vertex as both its end vertices is called a self-loop. There may be more

than one edge associated with a given pair of vertices, for example e4 and e5 in fig. .Such edges are

referred to as parallel edges.



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Q.7 What is a circular queue ? Write algorithms to implement the insertion and deletion operations.

Ans. A circular queue uses the same conventions as that of linear queue. Using Front will always point one

position counterclockwise from the first element in the queue. In order to add an element, it will be

necessary to move rear one position clockwise. Similarly, it will be necessary to move front one position,

clockwise each time a deletion is made.

Algorithm: Insertion

Input: (1) CQ,Circular Queue; (2)e, element to be inserted; (3)SIZE, size of the Circular Queue;(4)F, the front

pointer; (5) R, the rear pointer

Output: (1)C Q, updated; (2) F, updated; (3) R,updated

Method:

If(Isfull(CQ)) then

Print(‘overflow’)

Else

R=R mod SIZE +1;

CQ[R]=e

If(Isempty(CQ))

F=1;

If end

If end

Algorithm ends

Algorithm: Deletion

Input: (1) CQ, Queue; (2)SIZE, size of the CQ;(3)F, the front pointer; (4) R, the rear pointer

Output: (1)CQ, updated; (2) F, updated; (3) R,updated; (4)e, element if deleted;

Method:

If(Isempty(CQ)) then

Print(‘queue is empty’)

Else

e=CQ[F]



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If(F==R)

F=R=0;

Else

F=F mod SIZE +1;

If end

If end

Algorithm ends

Q.8 Write an algorithm to find the roots of a quadratic equation.

Ans.

Algorithm: Quadratic_solver

Input: a, b, c the co-effcients of the Quadratic Equation

Output: The two roots of the Equation

Method:

Disc=((b*b)-(4*a*c))

If (disc=0)

Display ‘roots are real and equal’

r1= -b/2a

r2= -b/2a

display r1

display r2

else

if(disc>0)

display ‘roots are real and distinct’

r1=(-b+sqrt(disc))/2a

r2=(-b+sqrt(disc))/2a

else

display ‘roots are complex’



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display’real part’,b/2a

display ‘imaginary part’ , sqrt(absolute_value_of(disc))

display ‘the two root exists in conjugates’

end_if

Algorithm ends

Q.9 Develop an algorithm to generate all the prime numbers between the given 2 limits.

Ans.

Algorithms: Primarily Testing

Input: n, number, Flag, test condition

Output: flag updated

Method

Flag=o

for( i=2 to n/2 is steps of +1 and flag=0 )

if (n%i=0) //n mod i

Flag=1

end if

end for

if (flag=0)

display ‘Number is prime’

else

Display ‘Number not prime’

end if

Algorithm ends

Assignment: TB (COMPULSORY)

Part A

I. Say whether the following statements are true or false.



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1) Definiteness is one of the properties of an algorithm. -----TRUE

2) Graph is a linear data structure. -----FALSE

3) A tree is a connected graph. -----TRUE

4) The data structure used by recursion is stack. -----FALSE

5) Queue works on the strategy “First in First out”. -----TRUE

II. Using suitable word or phrase fill up the blanks in the following sentences:

1) Performance Process is the process of executing a correct program on data sets and measuring the time

and space.

2) Tree is a Connected graph data structure.

3) For a graph with ‘n’ number of nodes the number of edges to form a tree is n-1.

4) “Last in First out” Data structure is referred to as Stack

5) A binary tree of depth ‘K’ has maximum of 2k+1

- 1number of

nodes.

6) A Simple graph is a graph without self loop and parallel edges.

7) The two methods of searching are linear search and binary search.

III. Write brief answers to the following questions:

Q.1 Define algorithm. What are its properties?

Ans. The formal representation of sequence of instructions is called an

Algorithm.

1) Input

2) Output

3) Definiteness

4) Effectiveness

5) Termination.

Q.2 Give atleast four real life examples where we use stack operations

Ans.

(a) The processing of procedure calls and their terminations in computer programming.

(b) Arrangement of Plates on over another. The plate at the bottom of the plate hype is washed and kept

first but, it is used or comes out last.

(d) Chapattis cooked first are placed at the bottom in the Tiffin and the last cooked id at the top in the

Tiffin.

(e) Arrangement of chairs on over another. The chair which is put in first lies last when comes out.

Q.3 Differentiate full and complete binary trees.

Ans. A “complete” binary tree is one which allows sequencing of the nodes and all the previous levels are

maximally accommodated before the next level is accommodated. i.e., the siblings are first accommodated

before the children of any one of them. And a binary tree which is maximally accommodated with all

leaves at the same level is called “full” binary tree. A full binary tree is always complete but complete

binary tree need not be full.

Q.4 What are the demerits of recursion?



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Ans. 1. Many programming languages do not support recursion; hence recursive mathematical function is

implemented using iterative methods.

2. Even though mathematical functions can be easily implemented using recursion it is always at the cost

of execution time and memory space.

3. A recursive procedure can be called from within or outside itself and to ensure its proper functioning it

has to save in some order the return addresses so that, a return to the proper location will result when thereturn to a calling statement is made.

4. The recursive programs needs considerably more storage and will take more time.

PART - B

Q.1(a) What are the characteristics of an algorithm? Describe with an example

Ans.

1) Input

2) Output

3) Definiteness

4) Effectiveness

5) Termination

Q.1(b) Write an algorithm to implement any three operations of a queue

Ans.

Algorithm: Create

Output: Q, Queue created

Method:

Declare Q[SIZE] //Array with size=SIZE

Declare and Initialize F=0,R=0

// Front and Rear pointers to keep track of the front element and the rear element respectively

Algorithm ends

Algorithm: Isempty

Input: Q, Queue



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Output: Boolean

Method:

If(F==0)

Return(yes)

Else

Return(no)

If end

Algorithm ends

Algorithm: Isfull

Input: Q, Queue

Output: Boolean

Method:

If(R==SIZE)

Return(yes)

Else

Return(no)

If end

Algorithm ends

Q.3(b) Design an algorithm to sort the elements using merge sort.

Ans.

Algorithm: MERGESORT

Input: low, high, the lower and upper limits of the list to be sorted

A, the list of elements

Output: A, Sorted list

Method:

If (low<high)

mid¬ (low + high)/2

MERGESORT(low, mid)

MERGESORT (mid, high)MERGE(A, low, mid, high)



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If end

Algorithm ends

Q.4(a) What are preorder, Inorder, postorder traversals of a binary tree?

Ans.

Pre-Order TraversalIn this traversal, the nodes are visited in the order of root, left child and then right child. i.e.,

1. Visit the root node first.

2. Go to the first left sub-tree.

3. After the completion of the left sub-tree, Go to the right sub-tree.

Here, the leaf nodes represent the stopping criteria. We go to the sibling sub-tree after the traversal of a

sub-tree. The pre-order traversal sequence for the binary tree shown in Fig. 6.3 is : A B D E G H C F I J K

In-Order Traversal

In this traversal, the nodes are visited in the order of left child, root and then right child. i.e., the left sub-tree is traversed first, then the root is visited and then the right sub-tree is traversed. Here also, the

leaf nodes denote the stopping criteria. The in-order traversal sequence for the above considered example

(Fig. 6.3) is: D B G E H A F J I K C

Post_Order Traversal

In this traversal, the nodes are visited in the order of left child, right child and then root. i.e., the left sub-

tree is traversed first, then the sibling is traversed next. The root is visited last. The post-order traversal for

the above example (Fig. 6.3) is: D G H E B J K I F C A.

Q.4(b) Design recursion algorithms to implement them and explain with the help of an example.

Ans. The sum of the integers to n is the sum of the integers through n -1 + n. The sum of the integers to n-1

is the sum to n -2 to n -1, etc. Eventually, we know that the sum of the first positive integer is 1.

Therefore, we can define a terminating condition for some small subset of the problem. The recursive

algorithm to achieve this is as follows:

Algorithm : SumPosInt

Input : n, the upper limit

Output : Sum of first n positive integers

Method:

if (n <= 0) // We only want positive integers

return 0;

else

if (n == 0) // Our terminating condition

return 1;

else

return (n + SumPosInt( n -1 ); // recursive step

if end

if end



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Algorithm ends

Q.5(a) What is binary search? Develop a recursive algorithm for binary search.

Ans. Binary search method is also relatively simple method. For this method it necessary to have the vector

in an alphabetical or numerically increasing order.

The algorithm for binary search.

Algorithm : binary search

Input : A, vector of n elements, K,search element

Output : low-index of k

Method:

Low =l, high=n

While(low<=high-1)

{ Mid=(low+high)/2

If(k<a[mid])

High=mid

Else

Low=mid

If end

}

While end

If(k=A[low])

{

Write(“search successful”)

Write(k is at location low)

Exit();

}

Else

Write(search unsuccessful);

If end;

Algorithm ends

Q.5(b) What are the two methods of representing a binary tree?

Ans. Binary Tree can be represented using the two methods:

1.Static allocation

2. Dynamic allocation

Q.7(a) What is validation and testing of algorithms?

Ans. Validation: Converting the algorithms into programs is a time consuming process. Hence, it essential

to be reasonably sure about the effectiveness of the algorithms before it is coded. This process, at the

algorithm level, is called “Validation”.



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Testing: The ultimate test of an algorithms is that the programs based on the algorithm should run

satisfactorily.

Q.7(b) Explain the terms with examples:

i) Finite graph : A graph with a finite number of vertices as well as a finite number of edges is

called a finite graph.

ii) Isolated and pendent vertices: A vertex having no incident edge is called an isolated vertex. A

vertex of degree one is called a pendent vertex or an end vertex.

iii) NULL graph: a graph, without any edges, is called a null graph.

iv) Path.: If a walk has the restriction of no repetition of vertices and no edge is retraced it is called

a “path”.

Q.8 Write short notes on :

a) Debugging : Debugging is the process of executing programs with sample datasets to determine if the

results obtained are satisfactory. When unsatisfactory results are generated, suitable changes are made in

the program to get the desiredresults, debugging can only indicate the presence of errors but not the

absenceof it”.

b) The need for recursion: 1. Mathematical functions such as factorial and fibonacci series generation can

be easily implemented using recursion than iteration.

2. In iterative techniques looping of statement is very much necessary.

c) Incidence matrix.: Let G be a graph with n vertices, e edges, and no self-loops. Define an n by e matrix A

=[aij], whose

n rows correspond to the n vertices and the e columns correspond to the e edges, as follows:

The matrix element

Aij = 1, if jth edge ej is incident on ith vertex vi, and

= 0, otherwise.

Incidence matrix of the graph in Fig.

Such a matrix A is called the vertex-edge incidence matrix, or simply incidence matrix. Matrix A

for a graph G is sometimes also written as A(G). A graph and its incidence matrix are shown in Fig.

and Fig. respectively. The incidence matrix contains only two elements, 0 and 1. Such a matrix is

called a binary matrix or a (0, 1)-matrix.

The following observations about the incidence matrix A can readily be made:

1. Since every edge is incident on exactly two vertices, each column of A has exactly two1’s.

2. The number of 1’s in each row equals the degree of the corresponding vertex.

3. A row with all 0’s, therefore, represents an isolated vertex.

a b c d e f g h

v1 0 0 0 1 0 1 0 0

v2 0 0 0 0 1 1 1 1v3 0 0 0 0 0 0 0 1



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v4 1 1 1 0 1 0 0 0

v5 0 0 1 1 0 0 1 0

v6 1 1 0 0 0 0 0 0

22

4. Parallel edges in a graph produce identical columns in its incidence matrix, for example, columns.



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Subject: JAVA Programming

Subject Code: BSIT - 42

Assignment: TA (Compulsory)

Q.1 Explain basic features of Java

Ans.

Simple : Java is designed as closely to C++ as possible in order to make the system more

comprehensible. Java omits many rarely used, poorly understood, confusing features of C++.

Object-Oriented : Object-Oriented languages allow the programmer to organize a program, so that

it closely models the real world in structure and in interactions among its components.

Distributed : Java includes pre-built components or libraries that provide important additional

capabilities beyond the language itself.

Interpreted : Java’s executables files are composed of bytecodes that are instructions and data

relating to a hypothetical computer called Java Virtual Machine. Each Machine that runs a Java

program uses a small program, known as the Java run-time system, to execute the Java bytecodes

in your program.

Robust : In Java programs, exceptions can be detected and handled according to instructions

written by the programmer, often allowing software to keep working in the face of unexpected

problems.

Secure : One of the potential errors of the internet is the possibility of security breaches viruses

that infect your computer, or hackers who take advantage of a software glitch to invade your

personal cyberspace and make off with confidential information.

Architecture Neutral : Java’s bytecodes are designed to be read and interpreted in exactly the same

manner on any computer hardware or operating system that supports a Java runtime. No

translation or conversions is necessary.

Portable : Java program contain no implementation dependent aspects, so the result of executing a

series of Java bytecodes should always be the same no matter on what system they are executed.

High Performance : A typical problem with interpreted languages is that they are somewhat less

efficient than complied languages. A program written by use of an interpreted language may run 20

to 100 times slower than the same program written by use of a compiled language



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Q.4 Explain the following OOPs concept :

a) object and classes : Object is a physical entity which represents a person, vehicle or a conceptual

entity(thing in existence) like bank account, company etc.

A set of variables and functions used to describe an object is a “class”.

A class defines the structure and behavior( data and code) that will be shared by a set of objects.

Each object of a given class contains the structure and behavior defined by the class, as if it were

stamped out of a mould in the shape of a class. A class is a logical construct, an object has physical

reality.

b) Abstraction : the act of leaving out of consideration one or more qualities of a complex object so as

to attend to others. Solving a problem with objects requires you to build the objects tailored to

your solution. We choose to ignore its inessential details, dealing instead with the generalized and

idealized model of the object.

c) Encapsulation : The ability to provide users with a well-defined interface to a set of functions in a

way, which hides their internal workings. In object oriented programming, the technique of keeping

together data structures and the methods( procedure) which act on them. The easiest way to think

of encapsulation is to reference phones.

d) Inheritance : Inheritance in object oriented programming means that a class of objects can inherit

properties from another class of objects. When inheritance occurs, one class is then referred to as

the parent class or superclass or base class. In turn, these serve as a pattern for a derived class or

subclass.

e) Polymorphism : Polymorphism is simply a name given to an action that is performed by similar

objects. Polymorphism allows a common data-generating message to be sent to each class and

allows each subclass object to respond a message format in an appropriate manner to its own

properties. Polymorphism encourages something we call ‘extendibility’. In other words, an object

or a class can have it’s uses extended.



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f) Message passing: In an object based world the only way for anything to happen is by objects

communicating with each other and acting on the results. This communication is called message

passing and involves one object sending a message to another and possibly receiving a result.

Q.5 What are the advantages of object oriented programming ?

Ans.

Reusability.

Modularity.

Security.

Easy Mapping

Scalability.

Easy Management.

Q.6 Explain the structure of a Java program.

Ans. Documentation Section: The documentation section comprises a set of comment lines giving the

name of the program , the author and other details. Java also uses comment /** …*/ known as

documentation comment.

Package Statement : the first statement allowed in a java file is a package statement. This statement

declares a package name and informs the compiler that the classes defined here belong to this package.

Import Statement : The next thing after a package statement( but before any class definitions) may be a

number of import statements. This is similar to the #include statement in C.

Interface Statements : An interface is like a class but includes a group of method declarations. This is also

an optional section and is used only when we wish to implement the multiple inheritance feature in the

program.

Class Definitions : A Java Program may contain multiple class definitions. Classes are the primary and

essential elements of a Java Program.



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Main Method Class : Since every stand-alone program requires a main method as its starting point, this

class is the essential part of a Java program. A simple Java program may contain only this part. The main

method creates objects of various classes and establishes communications between them.

Q.7 With an example explain Java tokens.

Ans. Java Language includes four types of token:

Reserved Keywords : Keywords are an essential part of a language definition. They implement

specific features of the language. Java language reserved 60 words as keywords. All keywords are to

be written in lower case letters. Ex. Abstract, break etc.

Identifiers : Identifiers are used for naming classes, methods, variables, objects, labels, package and

interfaces in a program. Ex. Average , sum , Batch_strength.

Literals : Literals in Java are a sequence of characters( digits ,letters, and other characters) that

represent constant values to be stored in variables.

Operators : An operator is a symbol that takes one or more arguments and operates on them to

produce a result.

Q.8 With an example explain different data types in Java.

Ans. Different types of data types of Java are :

Integer Types: Integer types can hold whole numbers such as 123 , -96 and 5639. The size of the values

that can be stored depends on the integer data type we choose. Java supports four types of integers , Byte

, Short , Int and Long.

Floating Point Types : There are two types for floating point numbers , float and double. They are used to

store number with values to the right of the decimal point. When you specify a literal value for a float, put

a capital F(float) to the right of the value to explicitly state that it is a float, not a double.

Character Types : Another data type you need to store and manipulates is single-character information.

The primitive type used for storing a single character is char. You can store only one character in a char

variable. If you want to store whole words you can use an object type called string.

Q.9 With an example explain all the operators in Java.



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Ans. Arithmetic Operators :There are five basic arithmetic operators in Java : Addition(+) , Subtraction (-),

multiplication(*) , division(/) and modulus(%). All operators can be used with all primitive numeric types(

char, byte , short, int, long float and double). In addition any two numeric types can be combined.

Although the operators can be used with any numeric type, Java actually only does arithmetic with the

types int, long, float and double.

Assignment Operators : Assignment operators are used to assign the value of an expression to a variable.

We have seen the usual assignment operator, ‘=’. In addition, Java has a set of ‘shorthand’ assignment

operators which are used in the form. Java also provides several short cut assignment operators that allow

perform an arithmetic , logical, or bitwise operation and an assignment operation all with one operator .Ex.

i=i+1;

you can shorten this statement:

i+=1;

Relational Operators: We often compare two quantities and depending on their relation, take certain

decisions. For examples, we may compare the age of two persons, or the price of two items, and so on.

These comparisons can be done with the help of relational operators.

Ex. a<b or x<20 where ‘<’ denotes less than

Logical Operators: Relational operators often are used with the conditional operators to construct more

complex decision making expressions. One such operator is &&, which performs the Boolean and

operation. For ex. you can use two different relational operators along with && to determine if both

relationships are true.

Q.10 With an example explain the following statements in Java.

a) simple if : The if statement is a powerful decision making statement and is used to control the flow

of execution of statements. The general form of a simple if statement is :

if(test expression)

{

Statement-block;

}

Statement-x;

The statement-block may be a single statement or a group of statements. If the test expression is

true, the statement-block will be executed.



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g) if..else: The if…else statement is an extension of the simple if statement. The general form is

if (Test expression)

{

True-block statement(s)

}

Else

{

False-block statement(s)

}

Statement-x

If the test expression is true, then the true-block statements, immediately following the if

statements are executed otherwise the false-block statement executed.

h) nested if: When a series of decision are involved, we may have to use more than one if…else

statement in nested form as follows:

if(test condition)

if(test condition)

{

Statement 1;

}

Else

{

Statement 2;

}

Else

{

Statement 3;

}

Statement x;

i) else..if ladder: There is another way of putting ifs together when multi path decisions are involved.

A multipath decision is a chain of ifs in which the statement associated with each else is an if. It

takes the following general form:

if(condition 1)



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Statement 1;

Else if(condition 2)

Statement 2;

Else if(condition 30

Statement 3

……………..

Else if(condition n)

Statement n;

Else

Default-statement;

Statement-x;

Q.11 With an example explain the switch statement in Java.

Ans. The switch is used far less often than if statement, but it is sometimes useful for expressing a certain

type of multi-way branch.

A switch statement allows you to test the value of an expression and, depending on that value, to jump to

some location within the switch statement. The expression must be either integer-valued or character-

valued. It cannot be string or a real number.

A switch statement has the form:

Switch (expression) {

Case 1:

Statements-1

Break;

Case 2:

Statements-2

Break;

.

. // more cases

.

Case n:

Statements-n

Break;

Default: //optional default case

// end of switch case



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}

Q.12 Compare while and do..while statements in Java.

Ans. The while statements contains a condition and a loop body. The condition Is enclosed within

parentheses .All the variables used in the condition of the while statements must be initialized before the

while loop. The value of the variables used in the condition must be changed in the loop body. Otherwise,

the condition may always remain true and the loop may never terminate. You change the values of the

variables by performing arithmetic operations on the variables.

Similar to the while statement, the do-while statement is a loop statement provided by Java. The

statement helps to perform certain repetitive actions depending on a condition.

The major difference between the do-while statement and the while statement is that in the while

statement, the loop body is executed only when the condition stated in the statement I true. In contrast, in

the do-while loop, the loop body is executed at least once, regardless of the condition evaluating to true or

false.

Q.13 With an example explain for statement in Java.

Ans To manage iterative actions, Java provides the for statement as an efficient alternative to the whole

statement creates a loop in which a set of statements is repeatedly executed until the specified condition

becomes false. The syntax of the for statement is:

For(Initialization expression; test condition; update expression)

{

Statement 1;

Statement 2;

}

The for statement starts with the for keyword. This statement had three elements enclosed within

parentheses.

Q.14 With the help of an example program explain break and continue statements in Java.

Ans. By using break, we can force immediate termination of loop, by passing the Conditional expression

and any remaining code in the body of the loop. When a break statement is encountered inside the loop,

the loop is terminated and program control resumes the next statement following the loop

Class Breakloop

{



[27]

Public static void main(string args[])

{

For(int i=0; i<00; i++)

{

If(i==10)

Break;

System.out.println(“i=:”+i);

}

System.out.println(“loop complete”);

}

}

The continue statement stops the current iteration of a loop and immediately starts the next iteration of

the same loop. When the current iteration of a loop stops, the statements after the continue statement in

loop are not executed.

Class EvenNum

{

Public static void main(String args[])

{

Int j,k;

For(j=1,k=0;j<=20;j++)

{

K=j%2;

If(k!=0)

Continue;

Else

System.out.println(j+ “is an even number”);

}

}

}



[28]

Assignment: TB (Compulsory)

PART-A

Q.1 How platform independence is achieved in JAVA ?

Ans. The java virtual machine

Garbage collection

Code security

Q.2 List any three features of JAVA

Ans. Simple, Object-oriented, Distributed.

Q.3 What is Java C, Javadoc and Jdbc?

Ans.Javac : translates java source code to byte code

Javadoc : creates html format documentation from java source file

JDBC : Is an API for the Java programming language that defines how a client may access a database.

Q.4 List different features of OOP.

Ans.

Objects and Classes

Abstraction

Encapsulation

Information Hiding

Inheritance

Polymorphism

Message passing

Q.5 Name different types of Java tokens.

Ans.

* Reserved Keywords

* Identifiers

* Literals

* Operators

Q.6 What is the task of the main method in Java program ?

Ans. Since every Java stand-alone program requires a main method as its starting point, this class is the

essential part of a Java program. A simple Java program may contain only this part. The main method

creates objects of various classes and establishes communications between them.



[29]

Q.7 Why can’t we use a keyword as a variable name ?

Ans. These keywords have specific meaning in Java, we cannot use them as names for variables, classes,

methods.

Q.8 Why main method in Java is declared as static ?

Ans. You specify that the main() method can be called without instantiating a particular instance of a class.

The keyword static helps you do this. This is necessary because the main() method is called by the Java

interpreter before any objects are created.

Q.9 Write an equivalence of switch statement and if statement

Ans. The switch is used far less often than the if statement, but it is sometimes useful for expressing a

certain type of multi-way branch.

A switch statement allows you to test the value of an expression and, depending on that value, to jump to

some location within the switch statement. The expression must be either integer-valued or character

valued. It cannot be a String or a real number.

The if statement is a powerful decision making statement and is used to control the flow of execution of

statements. It is basically a two-way decision statement and is used in conjunction with an expression.

Q.10 Constructor is _____________.

Ans. Constructors are similar to methods, but they are not methods. Like a method, a constructor has a

set of parameters and a body of code. Unlike methods, however, constructors have no return type.

PART - B

Q.1(a) What is inheritance and how one can achieve code reusability? Explain

with an example

Ans. Inheritance refers to the properties of a class being available to other classes as well. The original class

is called Base Class and Derived classes are classes created from the existing class (Base Class). It will have

all the features of the base class. The concept of Inheritance is very important in Object orientedprogramming languages.

import java.io.*;

//super class declaration

class book

{

String name;

int id;

void showsuper( )

{System.out.println("the id and name of the book is :" +id+ " " +name);

}



[30]

}

class book1 extends book

{

String author;

void showderived( )

{

System.out.println("the author name is:” +author);

}}

class simpleinhertence

{

public static void main(String args[ ])

{

book superob=new book( );

book1 subobj = new book1( );

superob.id=10;

superob.name="java";

System.out.println("the contents of super object is");superob.showsuper( );

System.out.println( );

subobj.id=20;

subobj.name=”C programming”;

subobj.author=”Balaguruswamy”;

System.out.println(“the contents of the subobj:”);

subobj.showsuper( );

subobj.showderived( );

}

}

Result

The contents of super object is

The id and name of the book is: 10 java

The contents of the subobj:

The id and name of the book is : 20 C programming

The author name is: Balaguruswamy

Q.1(b) What is a class? How does it accomplish data hiding? Explain with example.

Ans. A class defines the structure and behavior (data and code) that will be shared by a set of objects. Each

object of a given class contains the structure and behavior defined by the class

For example, you might have a Tree class that describes the features of all trees (has leaves and roots,

grows, creates chlorophyll). The Tree class serves as an abstract model for the concept of a tree-to reach

out and grab, or interact with, or cut down a tree you have to have a concrete instance of that tree. Of

course, once you have a tree class, you can create lots of different instances of that tree, and each

different tree instance can have different features (short, tall, bushy, drops leaves in Autumn), while still

behaving like and being immediately recognizable as a tree.

Q.2(a) Compare in terms of their functions and semantics the following pairs of

statements:



[31]

i) do while and while : the do-while statement and the while statement is that in the while statement, the

loop body is executed only when the condition stated in the statement is true. In contrast, in the do-while

loop, the loop body is executed at least once, regardless of the condition evaluating to true or false.

ii) while and for : The for statement creates a loop in which a set of statements is repeatedly executed

until the specified condition becomes false. The while statement contains a condition and a loop body. The

condition is enclosed within parentheses.

iii) nested if and switch : The effect of a break is to make the computer jump to the end of the switch

statement.

By using break, we can force immediate termination of loop, by passing the Conditional expression and any

remaining code in the body of the loop.

iv) break and continue : The effect of a break is to make the computer jump to the end of the switch

statement. By using break, we can force immediate termination of loop, by passing the Conditional

expression and any remaining code in the body of the loop.

The continue statement stops the current iteration of a loop and immediately starts the next iteration of

the same loop. When the current iteration of a loop stops, the statements after the continue statement in

the loop are not executed.

Q.3(a) Explain different data types in Java with example.

Ans. Integer types can hold whole numbers such as 123,-96,and 5639. The size of the values that can be

stored depends on the integer data type we choose. Java supports four types of integers. Byte, short, int,

and long.

There are two types for floating point numbers, float and double. They are used to store number with

values to the right of the decimal point.

Another data type you need to store and manipulate is single-character information. The primitive type

used for storing a single character is char.

Q.3(b) Describe the structure of a typical Java program.

Ans. A Java program may contain many classes of which only one class defines a main method. Classes

contain data members and methods that operate on the data members of the class. Methods may contain

data type declarations and executable statements. To write a Java program, we first define classes and

then put them together. A Java program may contain one or more sections as shown in the Fig.

Documentation Section

The documentation section comprises a set of comment lines giving the name of the program , the author

and other details. Java also uses comment /**…*/ known as documentation comment.

Package Statement



[32]

The first statement allowed in a Java file is a package statement. This statement declares a package name

and informs the compiler that the classes defined here belong to this package.

Eg : package student;

Import Statement

The next thing after a package statement (but before any class definitions) may be a number of import

statements. This is similar to the #include statement in C. Example :

Import student.test;

This statement instructs the interpreter to load the test class contained in the package student.

Interface Statements

An interface is like a class but includes a group of method declarations. This is also an optional section and

is used only when we wish to implement the multiple inheritance feature in the program.

Documentation Section Suggested

Package Statement Optional

Import Statements Optional

Interface Statements Optional

Class Definitions Optional

Main Method class

{

Main Method Definition

}

Essential

Class Definitions

A Java program may contain multiple class definitions. Classes are the primary and essential elements of a

Java program.

Main Method Class

Since every Java stand-alone program requires a main method as its starting point, this class is the

essential part of a Java program. A simple Java program may contain only this part. The main method

creates objects of various classes and establishes communications between them.

Q.4(a) What is JVM ? How does it help to achieve platform independence? If JVM is

available for windows then can we run program written on Unix platform ?



[33]

Comment.

Ans. All language compilers translate source code into machine code for a specific computer. Java

Compiler produces an intermediate code known as bytecode for a machine that does not exist. This

machine is called the Java Virtual Machine and it exists only inside the computer memory.

Q.5(a) Distinguish between the following terms:

i) Dynamic binding and message passing : Java’s program units, classes, are loaded dynamically (when

needed) by the Java run-time system.

Loaded classes are then dynamically linked with existing classes to form an integrated unit. The lengthy

link-and-load step required by third-generation programming languages is eliminated.

In an object based world the only way for anything to happen is by objects communicating with each other

and acting on the results. This communication is called message passing and involves one object sending a

message to another and (possibly) receiving a result.

ii) Inheritance and Polymorphism : Inheritance in object oriented programming means that a class of

objects can inherit properties from another class of objects. When inheritance occurs, one class is then

referred to as the ‘parent class’ or ‘superclass’ or ‘base class’. In turn, these serve as a pattern for a

‘derived class’ or ‘subclass’.

Poly means many...morph means change (or ‘form’). Many changes of form or changes of form by many.

Polymorphism allows a common data-gathering message to be sent to each class and allows each subclass

object to respond to a message format in an appropriate manner to its own properties.

Q.5(b) What are the difference between C and Java.

Ans.

a. Ans. Java does not have a preprocessor, and as such, does not have macros like define. Constants

can be created by using the final modifier when declaring class and instance variables.

b. Java does not include C’s const keyword or the ability to pass by const reference explicitly.

c. Java classes are single inherited, with some multiple-inheritance features provided through

interfaces.

d. All functions must be methods. There are no functions that are not tied to classes.

e. The goto keyword does not exist in Java(it’s reserved word, but currently unimplemented). You can,

however, use labeled breaks and continues to break out of and continue executing complex switch

or loop constructs.

f. Java does not use pointers.

g. Java doesn’t contain the data types: Struct, Union, Enum.

Q.6(a) Define programming. What are the types of programming? Explain.



[34]

Ans. Programming;- It is a method of implementation in which programs are organized as co-operative

collection of objects, each of which represents an instance of some class and whose classes all members of

a hierarchy of classes united in inheritance relationships.

Unstructured Programming

Usually, people start learning programming by writing small and simple programs consisting only of one

main program. Here “main program” stands for a sequence of commands or statements, which modify

data, which is global throughout the program.

Procedural Programming :

With procedural programming you are able to combine returning sequences of statements into one single

place. A procedure call is used to invoke the procedure. After the sequence is processed, flow of control

proceeds right after the position where the call was made

Modular Programming

With modular programming procedures of a common functionality are grouped together into separate

modules. A program therefore no longer consists of only one single part. It is now divided into several

smaller parts which interact through procedure calls and which form the whole program.

Object-Oriented Programming

In object oriented programming, a complex system is decomposed in accordance to the key abstractions of

the problem. Rather than decomposing the problems into steps, we identify objects, which are delivered

directly from the vocabulary of the problem domain.

Q.7(a) List and explain different types of loops in Java.

Ans.

THE WHILE LOOP

To perform an action repeatedly, Java provides certain loop statements. One of the loop statements is the

while statement. The while statement contains a condition and a loop body. The condition is enclosed

within parentheses.

Syntax:

While (test condition)

{

Body of the loop

};

DO STATEMENTThe statement helps to perform certain repetitive actions depending on a condition. The major difference

between the do-while statement and the while statement is that in the while statement, the loop body is

executed only when the condition stated in the statement is true. In contrast, in the do-while loop, the

loop body is executed at least once, regardless of the condition evaluating to true or false.

Syntax:

do

{

loop body

}while(condition);



[36]

(i) Trim : The trim method returns a copy of the invoking string from which any leading and trailing white

space has been removed. It has the general form:

String trim ( );

(ii) Substring : The Substring method is used to create new instances of the class String from existing

instances. The new string is specified by giving the required index range within the existing string .

string substring(int startIndex)

This returns the sub string that starts at startIndex and runs to the end of the invoking string.

string substring(int start Index, int endIndex)

This returns the substring that starts at startindex and runs through endIndex-1;

(iii) Length : The length of a string is the number of characters that it contains. To obtain this value call alength method str.length();



[37]

Subject: UNIX & Shell Programming



Q.1 How the Unix is different from other OS?

Ans. Unix is a multitasking operating system, which allows the computer to run several programs at the

same time. By going quickly from one task to another and performing a little bit of each task every time,

the operating system gives an impression of doing many things at the same time.

Q.2 What are Internal & External commands?

Ans. Some commands in Unix are internal, built into the shell. For example, the cd command is built-in.

The shell interprets the command and changes the current directory .On the other hand , cat command isan external program stored in the file/bin/cat. External commands require the shell to run a new sub

process; this takes some time ,especially if the system is busy.

Q.3 How do you change your password in Unix?

Ans. The system will prompt the user fir the old password. Once this is entered, the new password is

requested. The system once again prompts the user to retype the new password, to make sure that there

is no mistake in the entry.

Q.4 List various directory related commands

Ans.

Cd

Mkdir

Rmdir

Ls

Q.5 What are different types of files in Unix?

Ans. Syntax file filename(s) ,This command identifies the file as regular, directory or device file. Further

attempts at classification are done by testing each filename.

Ex : denote all files .Various types are identified by file.

$ file *

Abs.dat: ascii text

Absdel.cob: English text



[38]

Add.lst: empty

Q.6. Define Hard Links.

Ans. In Unix, a single copy of a file can have several names, which are links to the same file. Since all the

filenames refer to the same file, they have the same inode number. The second column in output of the Is-l

command gives the number of links that a file has. The number is 1 for unlinked files. Hard links can be

created using the ln command.

Q.7 What are absolute pathnames?

Ans. A pathname gives the file’s position in the file system An absolute or full pathname specifies the

location of a file in relation to the top of the file system which is the/(root). An absolute pathname starts at

the /(root) directory and lists each directory along the path to the destination file(or directory).

Q.8 When do we use “wc” command?

Ans. The command counts lines, words and characters in the file named depending on the option used.

Q.9 Explain the parent-child relationship in Unix file system.

Ans. In Unix all files are related to one another and are organized in a hierarchical structure. This is called

the UNIX file system and at the very top of the tree is the root directory, named ”/” which serves as the

reference point for all the files. The root directory has a number of subdirectories and files . Therefore,

every file expect the root will have a parent. A sample Unix file system tre..


PART - A

Q.1 What are the different standard given by POSIX ? What is POSIX ?

Ans. "Portable Operating System Interface [for Unix]"[1] is the name of a family of related standards

specified by the IEEE to define the application programming interface(API), along with shell and utilities

interfaces for software compatible with variants of the Unix operating system, although the standard can

apply to any operating system.

The POSIX specifications for Unix-like operating system environments originally consisted of a single

document for the core programming interface, but eventually grew to 17 separate documents.[3] The

standardized user command line and scripting interface were based on the Korn Sell. Many user-level

programs, services, and utilities including awk, echo, ed were also standardized, along with required

program-level services including basic I/O (file, terminal, and network) services. POSIX also defines a

standard threading library API which is supported by most modern operating systems. Nowadays, 10 out of

these 17 parts are combined into a single standard, IEEE Std 1003.1-2008, also known as POSIX:2008.



[39]

POSIX:2008: POSIX Base Definitions, System Interfaces, and Commands and Utilities (which include

POSIX.1, extensions for POSIX.1, Real-time Services, Threads Interface, Real-time Extensions, Security

Interface, Network File Access and Network Process-to-Process Communications, User Portability

Extensions, Corrections and Extensions, Protection and Control Utilities and Batch System Utilities).

Q.2 On which variable terminal setting is done ? Name any three terminal setting

keys.

Ans. The terminal settings are found in the TERM variable.

Terminal Setting Keys:-

[ctrl-h] erases text

[ctrl-c] or [Delete] Interrupts a command

[ctrl-d] Terminates a login session

[ctrl-s] stops screen scrolling

Q.3 Explain key features of UNIX.

Ans. UNIX goes beyond the traditional operating system by providing a standard set of libraries and

applications that developers and users can use. This standard interface allows application portability and

facilitates user familiarity with the interface.

Q.4 What is script command, with command explain how to create script file of a session?

Ans. Script is used to take a copy of everything which is output to the terminal and place it in a log file. It

should be followed by the name of the file to place the log in, and the exit command should be used to

stop logging and close the file. It can be used to obtain a copy of a program run, which should be placed

your notebook, and will be a required part of an assignment submission. Everything between the script and

the exit command is logged to the file. This includes the confirmation messages from script itself.

Q. 5 What happens if a directory permission charged?

Ans. The user mask is a numeric value that determines permissions when a file or directory is created.

Consequently, when a file or directory is created, its permissions are set to the permissions are set to the

permissions specified by the creating program minus the permission values denied by the unmask value.

Q.6 How do you yank and paste lines?

Ans. By giving Y command.

Q.7 List out the different attributes of a file.

Ans.

-rw-r-----

-rw-r -- r—

-rw-r – r—

drw-r -- r—



[41]

1) Process-ID(PID)

2) Parent PID(PPID)

PART - B

Q.1(a) Explain layered architecture of Unix operating system. With a suitable

command explain the interaction between Shell and Kernel.

Ans. The part of UNIX that manages the hardware and the executing processes is called the kernel. The

kernel is a collection of programs written in C which directly communicate with the hardware. Application

programs (user programs) communicate with the hardware by using the services of the kernel. Along with

the memory management, the kernel also schedules processes and decides their priorities. In the Unix

system, each hardware device is viewed as a file and is called a device file. This allows the same simple

method of reading and writing files to be used to access each hardware device. The file system manages

read and write access to user data and to devices, such as printers, attached to the system. It implements

security controls to protect the safety and privacy of information. In executing processes the kernel

allocates resources, including use of the CPU and mediates accesses to the hardware. The user commands

are translated into action by the shell which acts as an interpreter. The shell forms the outer part of the

operating system and forms the interface between the user and the kernel. For each user logged in, there

is shell in action. When a command is given by the user, it is examined by the shell and communicated to

the kernel for execution. The functions used to communicate with the kernel are called system calls and

are built into the kernel. The system calls are in all the flavors of UNIX are the same. Hence, software

developed on one UNIX system can be easily run on another UNIX system.

Q.1(b) Explain uname command with different options.

Ans. uname - displays the name of the operating system

Syntax

uname [ options ]

Examples:

Displays all the information

$ uname -a

SCO_SV sco5 3.2 5.0.5 i386



[42]

Displays the machine’s node name in the communications network.

$uname -n

sco5

Displays the operating system release.

$ uname -r

3.2

Displays the name of the operating system

$ uname -s

SCO_SV

Displays the operating system version

$ uname -v

5.0.5

Displays the information about system name, node name, operating system release number, kernel ID,

processor type, bus type, serial number, number of users license, OEM number, origin number and

number of CPUs.

$ uname -X

System = SCO_SV

Node = sco5

Release = 3.2v5.0.5

KernelID = 98/07/02

Machine = PentII

BusType = ISA

Serial = 5GE048977

Users = 5-user

OEM# = 0

Origin# = 1

NumCPU = 1



[43]

Q.2(a) Explain the advantages of ispell, list out the basic commands used in ispell.

Ans. The advantages of using ispell are as follows:

1)In the case of ispell, each word that does not appear in its dictionary will be displayed at the top of the

screen allowing the user to change it.

2) If the dictionary contains any near misses (i.e., words which differ by only a single letter, a missing or

extra letter, a missing space or hyphen or a pair of transposed letters,), ispell will display them.

3)ispell may display guesses at ways to make the word from a known root, with each guess preceded by

question marks.

4)ispell prints the line containing the word and the previous line at the bottom of the screen. If the

terminal can display in reverse video, ispell highlights the word itself. The user can then replace the word

completely, or choose one of the suggested words.

Q.2(b) Explain Unix file system and give the difference between relative and absolute

Pathname

Ans. While there is no standard Unix file structure go all flavors of Unix, there are some common

directories created at the time of Unix installation. The director structure of a typical Unix system is as

shown

The Absolute Pathnames: An absolute or full pathname specifies the location of a file in relation to the top

of the file system which is the /(root). An absolute pathname starts at the /(root) directory and list eachdirectory along the path to the destination file (or directory).

Relative pathnames: A relative pathname specifies a file in relation to the current directory and home the

relative pathname depends on the current directory. A relative pathname starts from the current

directory. In a relative pathname, a single dot (.) represents the current working directory and two dots (..)

represent the parent of the current working directory.

Q.3(a) Explain how to split file into multiple files. Give suitable example.

Ans. split - split large files into smaller files:

Syntax

split [options] filename prefix

where filename is the name of the large file to be split, prefix is the name to be given the small output files

and options can either be excluded or can be one of the following:

-l linenumber

-b bytes



[44]

If -l (the letter l) option is used, linenumber will be the number of lines to be put in each of the smaller files

(the default is 1,000). If the -b option is used, bytes will be the number of bytes to be put in each of the

smaller files.

The split command will give each output file created the name prefix with an extension attached to the

end to indicate its order. By default, the split command adds aa to the first output file, proceeding through

the alphabet to zz for subsequent files. If no prefix is specified, most systems use x .

Examples

Assuming that file.txt is 3,000 lines long, it will output three files, xaa, xab, and xac, and each one will be

1,000 lines long.

$ split file.txt

This will output six 500-line files: fileaa, fileab, fileac, filead, fileae, and fileaf.

$ split -l 500 file.txt file

Assuming that file.txt has 200 kilobytes, this will output five 40 kilobyte files: fileaa, filetab, fileac, filead

and fileae

$ split -b 40k file.txt file.

Q.3(b) Give the difference between Hard Link and Symbolic Link.

Ans. A symbolic link is a special file that contains the path name of the file to which it is linked. This is

unlike the hard link where in the linked file also contains the contents of the file to which it is linked.

Symbolic links are also called as soft links and are more flexible. They can be used to link to directories, orto files on other file systems. When a target file is deleted, a symbolic link to that file become unusable.

This is unlike a hard link where the contents of the file are preserved.

Q.4(a) What is a process? Explain the mechanism of creation in unix.

Ans. A process is born when a program starts execution and exists as long as the program is running after

execution the process is said to die the name of the process is usually the name of the program being

executed.

The mechanism of creation in UNIX:

The creation of a process is in three phases and uses three system calls known as fork, exec and wait. Fork

is a system call that creates a new process from an existing process. The new process is called the child

parent and child are an identical image except for parameters like PID. The child gets a new PID and the

process is forked this is the mechanism used to multiply processes in the system.

Q.4(b) List out the navigation keys for the cursor movement

Ans. In the command mode, navigation keys for the movement of the cursor by characters, words and

lines are as follows:

Keys movement of cursor



[45]

H cursor moves left

j cursor moves down

k cursor moves up

l cursor moves right

w word forward

b word backward

e end of word

^ first character

$ end of line

0 beginning of line

Q.5(a) Explain grep command with at least 5 examples with different options.

Ans. The grep command in UNIX is used to search for a pattern in a given file. It displays the selected

pattern, the line numbers or the filenames where the pattern occurs. The syntax is given below:

grep options pattern filename(s) grep searches for pattern in one or more filenames. The first argument is

the pattern and ones remaining are filenames. Let’s use grep to display lines containing the string

Information from the file emp.lst; the content of this file are shown below:

$ grep “Information” emp.lst

1001|T.N.Raju |Professor |Information Science|14/06/61|30000

1004|D.S.Raghu |Lecturer |Information Science|05/12/75|17000

1005|S.K.Anantha |Asst.Prof. |Information Science|20/07/63|24000

1002|Mallu |Lecturer |Information Science|20/07/74|15000

1003|B.S.Ashok |Lecturer |Information Science|01/01/78|15000

Examples

Ignoring Case (-i) When you look for a name, but are not sure of the case, grep offers the –i option which

ignores case for pattern matching:

$ grep -i “anantha” emp.lst


Deleting Lines (-v) grep can play an inverse role too; the –v (inverse) option selects all except lines

containing the pattern. Thus, you can create a file otherlist containing all but Lecturer.

$ grep -v “Lecturer” emp.lst > otherlist



[46]

1001|T.N.Raju |Professor |Information Science|14/06/61|30000


1006|H.R.Rajesh |Asst.Prof. |Mechanical |11/07/76|21000

Displaying Line Numbers (-n) The –n (numbers) option displays the line numbers containing the pattern,

along with the lines:

$ grep -n “Lecturer” emp.lst

2:1004|D.S.Raghu |Lecturer |Information Science |05/12/75|17000

4:1009|M.P.Rajendra|Sr.Lecturer |Computer Science |13/03/66|20000

5:1002|Mallu |Lecturer |Information Science |20/07/74|15000

8:1007|Sanjay |Lecturer |Civil |19/04/73|15000

Counting Lines Containing Pattern (-c) How many Lecturers are there in the file? The –c (count) option

counts the number of lines containing the pattern (which is not the same as number of occurrences). The

following shows that there are six of them:

$ grep -c “Lecturer” emp.lst

Matching Multiple Patterns (-e) With the –e option, you can match the two Mahanand by using grep like

this:

$ grep -e “mallu” -e “MALLU” emp.lst

1002|Mallu |Lecturer |Information Science|20/07/74|15000

Q.5(b) Explain Uniq command

Ans. When you concatenate or merge the files, you’ll face the problem of duplicate entr ies creeping in.

UNIX offers a special tool to handle these lines – the uniq command.

$ uniq dept.lst

Since uniq requires a sorted file as input, the general procedure is to sort file and pipe its output to uniq.

The following pipeline also produces the same output, except that the output is saved in a file uniqlist:

$ sort dept.lst | uniq – uniqlist

Q.6(a) Explain the mechanism of executing job periodically using cron.

Ans. A task can be automatically run in the background at regular intervals by a Unix utility called cron. The

cron daemon takes care of running these background jobs, which are called cron jobs.

A user can execute crontab if the user’s name appears in the file /usr/lib/cron/cron.allow. If the

cron.allow does not exist, the cron.deny file in /usr/lib/cron is checked. If the user’s name is not in this file



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the user is allowed to use crontab. If only cron.deny exists and is empty, all users can use crontab. If

neither file exists, only the root user can use crontab. The allow and deny files contain one user name per

line. The following options can be used with crontab:

crontab -e Edit your crontab file, or create one if it doesn’t already exist.

crontab -l Display your crontab file.

crontab -r Remove your crontab file.

An editor has to be specified to open the crontab file.

Q.6(b) Write a shell script to add two numbers by using Expr utility.

Ans. #/bin/sh

#Shell Script to Add two numbers

Sum='expa $1+$2'

echo $ sum

Here we defined a variable sum to hold the result of the operation. To run this script, we might type the

following line:

$ add 2 2

Then we get the sum are echoed on the screen

4

$

Q.7(a) What are positional parameters? Explain the command used to set the

positional parameters

Ans. A positional parameter is a variable within a shell program; its value is set from an argument specified

on the command line that invokes the program. Positional parameters are numbered and are referred towith a preceding ``$'': $1, $2, $3, and so on.

A shell program may reference up to nine positional parameters. If a shell program is invoked with a

command line that appears like this:

shell.prog pp1 pp2 pp3 pp4 pp5 pp6 pp7 pp8 pp9

then positional parameter $1 within the program is assigned the value pp1, positional parameter $2 within

the program is assigned the value pp2, and so on, at the time the shell program is invoked.

To practice positional parameter substitution, create a file called pp (short for positional parameters).

(Remember, the directory in which these example files reside must be in $PATH.) Then enter the echo



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current directory (.) and directory above (..)

-A all files including those beginning with a dot

(.).does not list current directory (.) and directory

above (..)

-d if an argument is a directory, lists only its name

(not its contents)

-F marks directories with a /, executables with a *

and symbolic links with a @

-I shows the inode number

-l lists in long format, giving mode, number of

links, owner, group, size in bytes, the time that each file was last modified.

-p puts a slash (/) after each directory.

s-r sorts the filenames in the reverse order

-R recursive list

-t sorts by time modified (latest first)

-u sorts by last access time

-x lists files in columns with entries sorted across



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Subject: Software Engineering



Q.1 Define Software Engineering as per IEEE.

Ans. According the IEEE, Software engineering is defined more comprehensive as “ The application of a

systematic, disciplined, quantifiable approach to the development, operation, and maintenance of

software, that is, the application of engineering of software.”

Q.2 Give important characteristics of the Prototype Model

Ans.

For prototyping, the cost of the requirements analysis must be kept low, in-order- for it to be

feasible.

The development approach followed is “quick and dirty”, the focus is on quicker development

rather than on the quality.

Only minimal documentation is required because it is throw away prototype model.

This model is very useful in projects where requirements are not properly understood in the

beginning.

It is an excellent method for reducing some types of risks involved with a projects.

Q.3 What is DFD?

Ans. Data Flow Diagram also called data flow graphs are commonly used during problem analysis, for

understanding a system. It shows the flow of data through the system it does not represent procedural

information. It views a system as a function that transforms the inputs into desired outputs.

Q.4 What are the two levels of Software design process?

Ans. The design process for the software has two levels:

System design

Detailed design



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Q.5 Name any 4 criteria used to guide modularization

Ans.

Modular Decomposability.

Modular Composability

Modular Understandability.

Modular continuity

Q.6 Define Cohesion

Ans. Cohesion is a measure of the relative functional strength of a module. It is an extension of information

hiding concept. A cohesive module must perform a single task within a software procedure., requiring little

interaction with procedures that are performed in other parts of a program.

Q.7 List any 3 popular Tabular Design Tools

Ans.

Decision Tables

Detailed State Diagrams and Tables

Karnaugh map.

Q.8 Why we require Coding standards and Practices?

Ans. When writing the code, many people are generally involved, and a great level of cooperation and

coordination is required . Thus, it is very important for others to understand not only what you have

written, but also why have written it and how it fits in their work. For these reasons, one must know theorganizations’ s standards and procedures before beginning to write code.

Q.9 What are Source code tools? Give example.

Ans. There are two commonly used source code tools-:

Editing tools, these relate to the editing of source code.

Browsing tools, helps to view the source code.



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Q.10 What is internal documentation?

Ans. Internal documentation is a descriptive material written directly with in the program, at a level

appropriate for a programmer. It contains information directed at some one who will be reading the

source code of the program .The information contains a description of data structures, algorithms and

control flow.

Q.11 Discuss the four major goals of SRS.

Ans.

It provides feedback to the customer. An SRS is the customer’s assurance that the development

organization understands the issues or problems to be solved and the software behavior necessary

to address those problems.

It decomposes the problem into component parts. The simple act of writing down software

requirements in a well-designed format organizes information, places borders around the problem,

solidifies ideas, and helps break down the problem into its component parts in an orderly fashion.

It serves as an input to the design specification . As mentioned previously, the SRS serves as the

parent document to subsequent documents, such as the software design specification and

statement of work.

It serves as a product validation check. The SRS also serves as the parent document for testing and

validation strategies that will to the requirements for verification.


PART – A

Fill up the blanks using suitable word or phrase in the following sentences:

1) Software is a set of instructions that when executed provide desired function

and performance.

2) Software is a process and product .

3) The Incremental method is also known as the iterative enhancement model.

4) An external entity is represented using rectangular box in a DFD.



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5) The software requirements deal with the requirements of the proposed system.

6) The weakest coupling that is most desirable is Data coupling.

7) The three important levels of abstraction are Procedural , Data and Control.

8) P.D.L. stands for Program Design Language.

9) Browsing Tools helps to view the source code.

10) Executable Code tools help in code creation, debugging and testing.

11) The two kinds of program documentation are Internal and External .

12) Estimation makes use of an important approach Decomposition.

13) PERT stands for Program Evaluation Review Technique.

II. Write brief answers to the following questions:

Q.1 Define the terms risk mitigation, risk monitoring.

Ans. Risk mitigation is a planning process. This process defines alternative ways to prevent risks and helps:

Avoid the identified risks from occurring.

Reduce the impact of the rick on the project.

It is a good practice to address possible ricks during the initial stages of project development. This

helps mitigate the probability of occurrence of ricks and the potential impact of ricks on the project

and its test process.

The risk mitigation strategies enable the following three risk management:: risk mitigation, risk monitoring,

risk management and contingency planning

The Risk monitoring activities commence as soon as project development begins and they are periodically

performed . It is not possible to frequently monitor all risks identified for the project and its test processtherefore, risks with relatively high priority are monitored more often than others. Following are the

primary objectives :

(1) To assess if the predicted risk really occur.

(2) To ensure that the risk avoidance steps defined for a particular risk are being properly

implemented.

(3) To collect information that cans be used for risk analysis in future



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Q.2 Name the important approaches used in program debugging.

Ans. It occurs as a consequence of successful testing when a test case uncovers an error, then debugging

process begins with the execution of test cases

There are three debugging approaches commonly used:

1) Brute force method: It is the most common and test efficient method. It is applied when all else

fails.

2) Back tracking: Fairly common, can be successfully used in small programs beginning at the site

where symptoms has been found the source code is traced backward until the site of course is found.

3) Cause elimination: Used the concept of binary partitioning. ”A cause HYPOTHESIS” is devised and

data related to the error occurrence are used to prove or disprove the hypothesis

Q.3 What are specification languages? Give an example.

Ans. A specification language is a formal language used in computer science. Unlike most programming

languages, which are directly executable formal languages used to implement a system, specification

languages are used during systems analysis, requirements analysis and systems design.

Specification languages are generally not directly executed. They describe the system at a much higher

level than a programming language. Indeed, it is considered as an error if a requirement specification is

cluttered with unnecessary implementation details, because the specification is meant to describe the

what, not the how.

A common fundamental assumption of many specification approaches is that programs are modeled as

algebraic or model-theoretic structures that include a collection of sets of data values together with

functions over those sets. This level of abstraction is commensurate with the view that the correctness of

the input/output behavior of a program takes precedence over all its other properties.

In the property-oriented approach to specification (taken e.g. by CASL), specifications of programs consist

mainly of logical axioms, usually in a logical system in which equality has a prominent role, describing the

properties that the functions are required to satisfy - often just by their interrelationship. This is in contrast

to so-called model-oriented specification in frameworks like VDM and Z, which consist of a simplerealization of the required behavior.

PART – B

Q.1(a) What is software? List out the important characteristics of software

Ans. Computer software, or just software, is a collection of computer programs and related data that

provide the instructions for telling a computer what to do and how to do it. In other words, software is a

conceptual entity which is a set of computer programs, procedures, and associated documentation

concerned with the operation of a data processing system. We can also say software refers to one or morecomputer programs and data held in the storage of the computer for some purposes. In other words



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software is a set of programs, procedures, algorithms and its documentation. Program software performs

the function of the program it implements, either by directly providing instructions to the computer

hardware or by serving as input to another piece of software. The term was coined to contrast to the old

term hardware (meaning physical devices). In contrast to hardware, software is intangible, meaning it

"cannot be touched".

Characteristics::

Software is Developed or Engineered

Not Manufactured

Software Does Not ´Wear Outµ

May Become Un-Maintainable

Hardware Does wear out

Most Software is Custom-Built

Limited Role for Packaged Products Which Need Customization and Integration With Other Apps.

Q.1(b) Explain the waterfall model of software process. What are its limitations?

Ans. The waterfall model is a sequential design process, often used in software development processes, in

which progress is seen as flowing steadily downwards (like a waterfall) through the phases of Conception,

Initiation, Analysis, Design, Construction, Testing, Production/Implementation and Maintenance. Thewaterfall development model originates in the manufacturing and construction industries: highly

structured physical environments in which after-the-fact changes are prohibitively costly, if not impossible.

Since no formal software development methodologies existed at the time, this hardware-oriented model

was simply adapted for software development) Describe the three generic views of software engineering.

The limitation of this model is that, it requires a complete set of user requirements before the

commencement of design . Which is difficult to give since requirements keep on changing according to

needs and time.

Q.2(a) Describe the three generic views of software engineering.

Ans. The Definition phase: the definition focuses on what . That is during definition, the software developer

attempts to identify what information is to be processed, what function and performance are desired,

what system behavior can be expected, what interfaces are to be established, what design constraints

exist, and what validation criteria are required to define a successful system.

The Development phase: the development phase, focuses on how. That is , during the software

development, a software engineer attempts to define how data are to be structured, how function is to be



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implemented as a software architecture, how procedures are to be implemented, how design will be

translated into a programming language, how testing will be performed etc.

The Maintenance Phase: the maintenance phase focuses on change that is associated with the software.

The four main changes that are encountered during this phase are: Correction , Adaptations,

Enhancement, prevention.

Q.2(b) List out the important characteristics of good SRS.

Ans. The characteristics of good SRS are:

Correct and complete:-

An SRS is correct if every requirement included in the SRS represents something required in the final

system. An SRS is complete if everything the s/w is supposed to do and the responses of the s/w to all

classes of input data are specified in the SRS. Completeness ensures that everything is indeed specified.

Unambiguous:-

An SRS is unambiguous if and only if every requirement state has one and only one interpretation.

Requirements are often written in natural language, which are inherently ambiguous. One way to avoid

ambiguities is to use some formal requirements specification language.

Verifiable:-

An SRS is verifiable if and only if every stated requirement is verifiable .A requirement is verifiable if there

exists some cost effective process that can check whether the final s/w meet that requirement.Unambiguity is essential for verifiability. As verification of requirements is often done through reviews, it

also implies that an SRS is understandable at least by the developer, the client and the users.

Consistent:-

An SRS is consistent if there is no requirement that conflicts with another. Terminology can cause

inconsistencies .This occurs if the SRS contains two or more requirements whose logical or temporal

characteristic cannot be satisfied together by any s/w system.

Modifiable :-

An SRS is modifiable if its structure and style are such that any necessary change can be made easily while

preserving completeness and consistency. Presence of redundancy is a major hindrance to modifiability as

it can easily lead to error.

Q.3(a) Give the outline structure of SRS

Ans. A sample of basic SRS outline

1. Introduction



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Purpose, Document conventions, Intended audience, additional information, Contact information/SRS

team members, Reference

2. Overall Descriptions

Product perspective, Product functions, User classes & characteristics, Operating environment, User

environment, Design/implementation constraints, Assumptions & dependencies

3 .External Interface requirements

User Interfaces, Hardware interfaces, Software interfaces, Communication protocol and interface

4. System Features

System feature A, Description and priority, Action/result, Functional requirement, System feature B

5. Other Nonfunctional Requirements

Performance requirements, Safety requirements, Security requirement, Software quality attributes, Projectdocument

6. Other requirements

Q.3(b) ) Why is design an important phase in software development life cycle? Describe design process.

Ans. The Design Phase :-In the design phase the architecture is established. This phase starts with the

requirement document delivered by the requirement phase and maps the requirements into an

architecture. The architecture defines the components, their interfaces and behaviors. The deliverable

design document is the architecture. The design document describes a plan to implement the

requirements. This phase represents the ``how'' phase. Details on computer programming languages and

environments, machines, packages, application architecture, distributed architecture layering, memory

size, platform, algorithms, data structures, global type definitions, interfaces, and many other engineering

details are established. The design may include the usage of existing components. The design phase is

summarized in Table above.

The architectural team can now expand upon the information established in the requirement document.

Using the typical and atypical scenarios provided from the requirement document, performance trade-offs

can be accomplished as well as complexity of implementation trade-offs.

Obviously, if an action is done many times, it needs to be done correctly and efficiently. A seldom used

action needs to be implemented correctly, but it is not obvious what level of performance is required. The

requirement document must guide this decision process. An example of a seldom used action which must

be done with high performance is the emergency shutdown of a nuclear reactor.

Analyzing the trade-offs of necessary complexity allows for many things to remain simple which, in turn,

will eventually lead to a higher quality product. The architecture team also converts the typical scenarios

into a test plan.

In our approach, the team, given a complete requirement document, must also indicate critical priorities

for the implementation team. A critical implementation priority leads to a task that has to be done right. If



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it fails, the product fails. If it succeeds, the product might succeed. At the very least, the confidence level of

the team producing a successful product will increase. This will keep the implementation team focused.

Exactly how this information is conveyed is a skill based on experience more than a science based on

fundamental foundations.

Q.4 Outline programming guidelines with regard to;

i) Control structures: In computer programming, a control structure is a programming language construct

which affects the flow of the program's execution.

For example, many language provide "if" statements, which allow the program to execute one set of code

if a statement is true, and another set of code if the statement is false. In the C programming language, this

might look like this:

if( x == 0 )

doSomething();

else

doSomethingElse();

Common control structures include while-loops, for-loops and if-statements, but there are many others as

well. The exact set of control structures depends on the programming language you're using.

ii) Algorithms: A step-by-step method of solving a problem or making decisions, as in making a diagnosis.

It is an established mechanical procedure for solving certain mathematical problems.

Prosperities of the algorithm

1) Finiteness: - an algorithm terminates after a finite numbers of steps.

2) Definiteness: - each step in algorithm is unambiguous. This means that the action specified by the step

cannot be interpreted (explain the meaning of) in multiple ways & can be performed without any

confusion.

3) Input :- an algorithm accepts zero or more inputs

4) Output :- it produces at least one output.

5) Effectiveness:- it consists of basic instructions that are realizable. This means that the instructions can be

performed by using the given inputs in a finite amount of time.

iii) Data structures: In computer science, a data structure is a particular way of storing and organizing data

in a computer so that it can be used efficiently.

Different kinds of data structures are suited to different kinds of applications, and some are highly

specialized to specific tasks. For example, B-trees are particularly well-suited for implementation of

databases, while compiler implementations usually use hash tables to look up identifiers.



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Data structures are used in almost every program or software system. Data structures provide a means to

manage huge amounts of data efficiently, such as large databases and internet indexing services. Usually,

efficient data structures are a key to designing efficient algorithms. Some formal design methods and

programming languages emphasize data structures, rather than algorithms, as the key organizing factor in

software design.

iv) General guidelines: This guidance applies to:

• Software used as a component, part, or accessory of a medical device;

• Software that is itself a medical device (e.g., blood establishment software);

• Software used in the production of a device (e.g., programmable logic controllers in manufacturing

equipment); and

• Software used in implementation of the device manufacturer's quality system (e.g., software that records

and maintains the device history record).

Q.5(a) What is software testing ? Describe the two ways of testing any engineered

software product

Ans. Software testing is an investigation conducted to provide stakeholders with information about the

quality of the product or service under test. Software testing also provides an objective, independent view

of the software to allow the business to appreciate and understand the risks of software implementation.

Test techniques include, but are not limited to, the process of executing a program or application with the

intent of finding software bugs (errors or other defects).

UNIT TESTING:: In computer programming, unit testing is a method by which individual units of source

code are tested to determine if they are fit for use. A unit is the smallest testable part of an application. In

procedural programming a unit may be an individual function or procedure. In object-orientedprogramming a unit is usually a method.[citation needed] Unit tests are created by programmers or

occasionally by white box testers during the development process.

INTERGATION TESTING:: Integration testing (sometimes called Integration and Testing, abbreviated "I&T")

is the phase in software testing in which individual software modules are combined and tested as a group.

It occurs after unit testing and before system testing. Integration testing takes as its input modules that

have been unit tested, groups them in larger aggregates, applies tests defined in an integration test plan to

those aggregates, and delivers as its output the integrated system ready for system testing.



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Q.5(b) What is the difference between verification and validation ?

Ans. Verification ensures the product is designed to deliver all functionality to the customer; it typically

involves reviews and meetings to evaluate documents, plans, code, requirements and specifications; this

can be done with checklists, issues lists, walkthroughs and inspection meetings. You CAN learn to do

verification, with little or no outside help.

Validation ensures that functionality, as defined in requirements, is the intended behavior of the product;validation typically involves actual testing and takes place after verifications are completed.

Difference between Verification and Validation:

Verification takes place before validation, and not vice versa. Verification evaluates documents, plans,

code, requirements, and specifications. Validation, on the other hand, evaluates the product itself. The

inputs of verification are checklists, issues lists, walkthroughs and inspection meetings, reviews and

meetings. The input of validation, on the other hand, is the actual testing of an actual product. The output

of verification is a nearly perfect set of documents, plans, specifications, and requirements document. The

output of validation, on the other hand, is a nearly perfect, actual product.

Q.6(a) Describe the different kinds of software development team structure

Ans. Waterfall development

The Waterfall model is a sequential development approach, in which development is seen as flowing

steadily downwards (like a waterfall) through the phases of requirements analysis, design, implementation,

testing (validation), integration, and maintenance. The first formal description of the method is often citedas an article published by Winston W. Royce[3] in 1970 although Royce did not use the term "waterfall" in

this article prototyping

Software prototyping, is the development approach of activities during software development, the

creation of prototypes, i.e., incomplete versions of the software program being developed.

Incremental development

Various methods are acceptable for combining linear and iterative systems development methodologies,

with the primary objective of each being to reduce inherent project risk by breaking a project into smallersegments and providing more ease-of-change during the development process.

Spiral development

The spiral model is a software development process combining elements of both design and prototyping-

in-stages, in an effort to combine advantages of top-down and bottom-up concepts. It is a meta-model, a

model that can be used by other models.

Q.6(b) What is COCOMO model? Explain the basic COCOMO model



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Ans. The Constructive Cost Model (COCOMO) is an algorithmic software cost estimation model developed

by Barry Boehm. The model uses a basic regression formula, with parameters that are derived from

historical project data and current project characteristics.

COCOMO consists of a hierarchy of three increasingly detailed and accurate forms. The first level, Basic

COCOMO is good for quick, early, rough order of magnitude estimates of software costs, but its accuracy is

limited due to its lack of factors to account for difference in project attributes (Cost Drivers). Intermediate

COCOMO takes these Cost Drivers into account and Detailed COCOMO additionally accounts for the

influence of individual project phases.

Q.7(a) Define the terms: quality, quality assurance and quality control.

Ans. Quality:: Software quality measures how well software is designed (quality of design), and how well

the software conforms to that design (quality of conformance), although there are several different

definitions, including conformance to customer expectations. It is often described as the 'fitness for

purpose' of a piece of software.

Whereas quality of conformance is concerned with implementation (see Software Quality Assurance),

quality of design measures how valid the design and requirements are in creating a worthwhile product.

Quality Assurance:: Quality assurance, or QA for short, is the systematic monitoring and evaluation of the

various aspects of a project, service or facility to maximize the probability that minimum standards of

quality are being attained by the production process. QA cannot absolutely guarantee the production of

quality products.

Two principles included in QA are: "Fit for purpose" - the product should be suitable for the intended

purpose; and "Right first time" - mistakes should be eliminated. QA includes regulation of the quality of

raw materials, assemblies, products and components, services related to production, and management,

production and inspection processes.

Quality Control :: Quality control is a process by which entities review the quality of all factors involved in

production. This approach places an emphasis on three aspects.

Elements such as controls, job management, defined and well managed processes, performance and

integrity criteria, and identification of records Competence, such as knowledge, skills, experience, and

qualifications Soft elements, such as personnel integrity, confidence, organizational culture, motivation,

team spirit, and quality relationships.

Q.7(b) Mention the objectives of formal technical review.

Ans. A software technical review is a form of peer review in which "a team of qualified personnel ...

examines the suitability of the software product for its intended use and identifies discrepancies f rom

specifications and standards. Technical reviews may also provide recommendations of alternatives and

examination of various alternatives"



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"Software product" normally refers to some kind of technical document. This might be a software design

document or program source code, but use cases, business process definitions, test case specifications,

and a variety of other technical documentation, may also be subject to technical review.

Technical review differs from software walkthroughs in its specific focus on the technical quality of the

product reviewed. It differs from software inspection in its ability to suggest direct alterations to the

product reviewed, and its lack of a direct focus on training and process improvement. The term formal

technical review is sometimes used to mean a software inspection.

Q.8. Write short notes on:

a) Software engineering: Software engineering (SE) is a profession dedicated to designing, implementing,

and modifying software so that it is of higher quality, more affordable, maintainable, and faster to build. It

is a "systematic approach to the analysis, design, assessment, implementation, test, maintenance and

reengineering of software, that is, the application of engineering to software."

b) The spiral model of software process:: The spiral model is a software development process combining

elements of both design and prototyping-in-stages, in an effort to combine advantages of top-down and

bottom-up concepts. Also known as the spiral lifecycle model (or spiral development), it is a systems

development method (SDM) used in information technology (IT). This model of development combines the

features of the prototyping model and the waterfall model. The spiral model is intended for large,

expensive and complicated projects.

c) Programming tools:: A programming tool or software development tool is a program or application that

software developers use to create, debug, maintain, or otherwise support other programs andapplications. The term usually refers to relatively simple programs that can be combined together to

accomplish a task, much as one might use multiple hand tools to fix a physical object.



~REFERENCES~

1.Course Materiel Provided.

2.http://www.javatpoint.com

3. http://www.tutorialspoint.com/unix/

http://www.tutorialspoint.com/unix/



assignment 5 sem

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