main index contents 11 main index contents storage containers -generalgeneral -vectors (3...

1 Main IndexMain Index ContentsContents1 Main IndexMain Index ContentsContents

Storage ContainersStorage Containers -General-Vectors (3 slides)-Lists-Maps

ADT’s (2 slides)

ClassesClasses-Declaration-Private/Public Sections (3 slides)

time24 function addTime()

Chapter 1 Chapter 1 – – Introduction to Object TechnologyIntroduction to Object Technology

Scope Resolution Operator

Rectangle Class (4 slides)

APIAPI-Constructor-Operations-randomNumber Class (2 slides)

Generating Random Numbers

String Functions and Operations (6 slides)

Summary Slides (9 slides)

2 Main IndexMain Index ContentsContents

Storage Containers Storage Containers ( General )( General )

Airlines and telecommunication Airlines and telecommunication companies use a grid of nodes and companies use a grid of nodes and

interconnecting edges to represent cities interconnecting edges to represent cities and routers in a network.and routers in a network.

Containers such as vectors, lists or maps Containers such as vectors, lists or maps are storage structures that provide ways are storage structures that provide ways to access data and insert/delete items.to access data and insert/delete items.

ExampleExample


Storage Containers Storage Containers ( Vectors)( Vectors)

A vector has all of the nice indexing features of an array along with the ability to dynamically grow to meet demand.

// output elements of v

for (i = 0; i < v.size(); i++)

cout << v[i] << " "

Output: 7 4 9 3 1



A vector is a "super-array“, meaning all familiar array algorithms work.

You also have the freedom to to grow or shrink it.

7 4 9

7 4 9 3 1 0 0 0

7 4 9 3

vec to r v (w ith 5 e lem en ts )

v.res ize (8 ); (gro w to 8 e lem en ts )

1

v.res ize (3 ); (sh rin k to 3 e lem en ts )



Vectors allow for direct access to their elements through an index, but are not efficient storage structures for: – insertion of items at arbitrary positions in a list. – deletion of items at arbitrary positions in a list.

3 0 3 51 5 2 0 3 0 3 5

1 5 2 0 3 0 3 51 5 2 0 3 0 3 5 4 0

4 02 5

4 0

1 5 4 0

2 0


Storage Containers Storage Containers ( Lists )( Lists )

list container – each element has a reference that identifies

the next item in the list. – Adding a new item involves breaking a link

in the chain and creating two new links to connect the item.

fro n t re a r

/ /

n e w Ite m


Storage Containers Storage Containers ( Maps )( Maps )

maps use a tree structure to store data. – A is a container that stores

elements as nodes emanating from a root.TREETREE

TV 93

W 29Z

N T2P

D 29Z

F A 27

B 40A

R o o t

G 9B 7

H 14K


Abstract Data TypesAbstract Data Types

ADT Operation Description operationName: Action statement that specifies

the input parameters, the type of operation on the elements of the data structure, and the output parameter

Preconditions: Necessary conditions that must apply to the input parameters and the current state of the object to allow successful execution of the operation.

Postconditions: Changes in the data of the structure caused by the operation.


Abstract Data TypesAbstract Data Types( time24 Class )( time24 Class )

duration(t): Time t is an input parameter. Measure the length of time from the current time to time t and return the result as a time24 value.

Precondition: Time t must not be earlier than the current time

9 3 0 1 0 2 0(a)

(b)

T im e (B efo re) T im e (A fter)

O p eratio n:ad d T im e (5 0 )

1 4

45 C urrent T im e

1 6 1 5

T im e t

O p eratio n:d uratio n ( t ) 1 3 0

R eturn tim e


ClassesClasses( Declaration )( Declaration )

CLASS className Declaration class className { public: // <public member function prototypes> . . . . . . . . private: // <private data members> . . . . . . . . // <private member function prototypes> . . . . . . . . };


Classes Classes ( Private/Public Sections)( Private/Public Sections)

The public and private sections in a class declaration allow program statements outside the class different access to the class members.

pr i vate :

data m e m be rsm e m be r func t io ns

publ i c :

a c c e s s ib le to theim ple m e nta tion of

the m e m be r func tionsac c e s s ible by

any pro gram s tate m e ntdata m e m be rsm e m be r func t io ns



Public members of a class are the interface of the object to the program.– Any statement in a program block that declares an

object can access a public member of the object

publ i c :

a c c e s s ib le to theim ple m e nta tion of

the m e m be r func tionsac c e s s ible by

any pro gram s tate m e ntdata m e m be rsm e m be r func t io ns



The private section typically contains the data values of the object and utility functions that support class implementation.– Only member functions of the class may access

elements in the private section.

pr i vate :

data m e m be rsm e m be r func t io nsa c c e s s ib le to the

im ple m e nta tion ofthe m e m be r func tions


Runtime execution of the time24 Runtime execution of the time24 function addTime()function addTime()

9 3 0

O bje c t t (B e fo re )

STATE M E N T: t .addTim e (7 5 ) ;

7 5

L ite ral 7 5

c o py7 5

Argum e nt m

Func tio n c al l

1 0 4 5

O bje c t t (Af te r )


Scope resolution OperatorScope resolution Operator The symbol "::" signals the compiler that the

function is a member of the class.– The statements in the function body may access all

of the public and private members of the class.

The “::” operator allows you to code a member function like any other free function.

returnType className::functionName(argument list)

{

<C++ statements>

}


CLASS rectangle Declaration “d_rect.h”

// maintains measurement properties of a //rectangle

class rectangle{public:// constructor. initializes length and // width

rectangle(double len = 0.0, double wid = 0.0): length(len), width(wid){}



// return the area (length * width)double area() const{ return length * width; }

// return the perimeter (2 * (length + // width))

double perimeter() const{ return 2 * (length + width); }



// change the dimensions of the// rectangle to len and wid

void setSides(double len, double wid){length = len;width = wid;

} // return the length of the rectangle

double getLength() const{ return length; }



// return the width of the rectangledouble getWidth() const{ return width; }

private:double length, width;

};


APIAPI( Constructor )( Constructor )

CLASS className Constructors “<file>.h”

className(<arguments>);Initializes the attributes of the object

Postconditions: Initial status of the object


API API ( Operations )( Operations )

CLASS className Operations “<file>.h”

returnType functionName(argument list);Description of the action of the function and any return value

Preconditions: Necessary state of the object before executing the operation. Any

exceptions that are thrown when an error is detected.

Postconditions: State of the data items in the object after executing the operation ….


API API ( randomNumber Class)( randomNumber Class)

CLASS randomNumber Constructors “d_random.h”

randomNumber(int seed = 0);Sets the seed for the random number

generatorPostconditions: With the default value 0, the system clock initializes the seed; otherwise the user provides the seed for the generator


API API ( randomNumber Class)( randomNumber Class)

CLASS randomNumber Operations “d_random.h”

double frandom();Return a real number x, 0.0 <= x < 1.0

int random();Return a 32-bit random integer m, 0 <= m <

231-1int random(int n);

Return a random integer m, 0 <= m < n


Generating Random NumbersGenerating Random Numbers

The loop generates 5 integer random numbers in the range 0 to 40 and 5 real random numbers in the range 0 to 1. int item, i;double x;

for (i = 0; i < 5; i++){item = rndA.random(40);// 0 <= item < 40

x = rndB.frandom();// 0.0 <= x < 1.0

cout << item << " " << x;}


String Functions and OperationsString Functions and Operations

int find_first_of(char c, int start = 0):Look for the first occurrence of cc in the string beginning at index startstart. Return the index of the match if it occurs; otherwise return -1. By default, startstart is 0 and the function searches the entire string.



int find_last_of(char c): Look for the last occurrence of cc in the string. Return the index of the match if it occurs; otherwise return -1.Since the search seeks a match in the tail of the string, no starting index is provided.



string substr(int start = 0, int count = -1):Copy count characters from the string beginning at index startstart and return the characters as a substring. If the tail of the string has fewer than count characters or count is -1, the copy stops at end-of-string. By default, startstart is 0 and the function copies characters from the beginning of the string. Also by default, the function copies the tail of the string.



int find(const string& s, int start = 0):The search takes string ss and index start and looks for a match of ss as a substring. Return the index of the match if it occurs; otherwise return -1. By default, startstart is 0 and the function searches the entire string.



void insert(int start, const string& s):Place the substring ss into the string beginning at index startstart. The insertion expands the size of the original string.



void erase(int start = 0, int count = -1): Delete count characters from the string beginning at index startstart. If fewer than count characters exist or count is -1, delete up to end-of-string. By default, startstart is 0 and the function removes characters from the beginning of the string.

Also by default, the function removes the tail of the string.

Note that no arguments at all truncates the string to the empty string with length 0


Summary Slide 1Summary Slide 1

§- A data structure is a systematic way of organizing and accessing data.

§- Programmer-defined data structures bundle data with operations that manipulate the data.

§- The structures, called containers have operations to access, insert, and remove items from the

collection.



§- Arrays have some limitations:

1) fixed size.

2) No automatic growth to meet the needs of an application. (Solution -> Use Vector Containers)

3) insertion and deletion inside the array requires the costly movement of data either to the right or to the left. (Solution -> Use List Containers)

§- Efficient access to an element requires knowledge of its position in the list.



§- Abstract Data Types (ADT’s) are a model used to understand the design of a data structure.

§- ADT’s specify the type of data stored and the operations that support the data.

§- Viewing a data structure as an ADT allows a programmer to focus on an idealized model of the data and its operations.


Summary Slide 3aSummary Slide 3a

§- An ADT provides simple and clear description of:

1) the input to an operation.

2) the action of the operation.

3) its return type.

§- PreconditionsPreconditions: Part of the description of an operation. A listing of the conditions that must apply

in order for the operation to execute successfully.

§- PostconditionsPostconditions: Indicate changes to the object's data caused by the operation. Necessary

because operations often alter the value of data.



§- The private section of a class contains the data and operations that the public member functions use in their implementation.

§- The splitting of a class into public and private parts is known as information hiding.

§- A class encapsulates information by bundling the data items and operations within an object.



§- The implementation of C++ class member functions is different from the implementation of free

functions.

- Each function name must include the class scope operator :::: that designates class membership.

§- The constructor is a special function with no return type.

- The constructor initializes the data members of the class by using its initialization list.



§- A member function can be implemented inside the class declaration by using inline code.

1) The semicolon (;;) in the function prototype is replaced by the function body.

2) The compiler inserts the statements in the function body in place of the function, avoiding the function call and return mechanism.

§- The process provides efficiency at the expense of increased code size.



§- Application Programming InterfaceApplication Programming Interface:

- Allows other programmers to use the public interface of the class without having to view the technical details of the class declaration or implementation.



§- C++ provides two approaches to string handling.

1)1) Older MethodOlder Method:C-style string - a character array that

designates the end of the string by using the NULL character. §- Used by the C programming language and older C++ programs.

2) 2) Modern MethodModern Method:

string class - provides a large public interface containing many useful operations.

§- Example: I/O operations.

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data structure

type of data

objects data

value of data

costly movement of data

operations string functions

abstract data types