chapter 2 basic element of programming

Chapter 2 : Basic Element of Programming Language and

Sequential Structure

Lecture Outline

Basic Element of Computer Program- General Overview

Data Manipulation- Standard data type (int, float, double, char, char[ ])- Variable

Computer Statement - Statement (constant, identifier)- Input/output statement - Arithmetic expression- Assignment concept

Basic Element of Computer Program

Comp. Statements

Sequence Selection Iteration

Problem Solving using Computer

Instruction/Steps Data

2

2

3 4

5

6Comp. ProgramProcedural Programming vsObject-oriented Programming

Functions•Independent•Method

Variable

Input /output

•Data type•Predefine/user define•Identifier•Size•Range•Lifespan•Scope

Data Manipulation

Types of data :1. Input data – key in by the user (need to solve the problem)2. Output data – process by the program and display to the user3. Temporary data – used by the program in the process of obtaining

the output data.

Data is presented by a variable in a computer program.Variable is a location in the computer’s memory where a value can be stored for use by a program.

Elements of the variable :Data Type (Pre Defined / User Defined)Lifespan – How long will the variable exist?Scope –Where can the variable being used?Identifier – Rules in using identifier

Pre Define Data Type (Size, modifier and range) Example : int, float, char and double

Data Type Modifiers Size (bytes) Rangeint Short, unsigned 2 0 to 65,535

Short, signed 2 -32,768 to 32, 767

Long, unsigned 4 0 to 4,294,967,295

Long, signed 4 -2,147,483,683 to 2,147,483,687

char 1 256 valuesfloat 4 1.2e-38 to 3.4e38

double 8 2.2e-308 to 1.8e308

Data Manipulation (cont.)

User Defined Data type – defined by user Example: object and array

Computer Statement

Program is a list of instruction that represented by the computer statement.

Language element than can be used in constructing high-level language programming form computer statement is called as Token.

6 types of token in C++ programming language :Reserved word IdentifierConstantString LiteralPunctuationOperator

Type of Token Description Example

Computer Statement (cont.)

Word that has a special meaning to compilerMust be typed in the correct locationMust be spell correctly (lower case letter)Must be used in the right context

Name which is used in a computer programOther than reserved wordMainly to name variables and functionRules :

consists of letters A..Z, a..z, 0..9, and _1st character must be a letterCase sensitivelength : < 32 character, recommended3 – 8 charactersMeaningful name

Reserved word

main( ), int, strcpy

Identifier Salary, SUM, PRO_10



Item with a fixed value (not be changed in any statement)Literal Constant – value typed directly,

wherever it is neededSymbolic Constant – represented by a name using a preprocessor directive of keyword const

Sequence of character surrounded by double quotation marksString literals may contain printable characters as \a, \n.

Constants

String Literals “ \n The minimum value is :”

int pie = 3.142

#define max 10.9const int size = 5



Separators in C++To limit the various syntactical units in

programming language

Result in computation or action when applied to variables or other elements in an expressionOperator act on operandUnary operator – operator that require one operandBinary operator – operator that require two operandTrenary operator – operator that required 3 operand (conditional operator (?:)

Punctuator

Operator

[ ], ( ), ;, *, #

+, -, *, <>, !=

A++, C—Total = sum + salarycout << (grade > 60 ? “ Passed” : “Failed”)

Several token will form a Statement.

Statement is an instructions to the computer.

Computer statement is a specification of an action to be executed by the computer. It is cause the processor to do something.

Example :

An input statement will input value and placed it to a variable

An output statement will print message or result to the user on the computer screen

Compound statement is a list of statement enclosed in braces { } that can contain declaration and any type of computer statement.


Types of computer statement

Input statementProcess statementOutput statement

Input statement – read the value for one or more variable from the input/user.

Format : Pre Defined data type variable

cin >> variable1 >> variable2 …. >>variablen;

Example :

cin>> first >> middle >> last;


Input Statement

Input statement for user defined data type variable

Example: array – use getline command

string name;

char name[20];

Format :

// I) use the string data type

getline (cin, variable_name)

or

// II) user know the maximum number of characters will be used

cin .getline (variable_name, number_of_characters);

Example

getline(cin, name)

cin.getline(name,20)

Output Statement

Output statement - print the value of one or more expressions.

Format : cout << expression1 << expression2 << … << expressionn;

Example :cout << ringgit;cout << “ Total value : “ << ringgit<<endl;

Print format : endl – cursor go to next line\n - cursor go to next line\t - the print out will tab the printout etc ..

Process Statement

Process statement – to ask processor to an actionTypes of process statement :

Assignment statementFunction call statement

Assignment statement – to store the given value or value of an expression in a variable

Format :variable = expression;

Example :sum = ringgit * 0.01 ;ringgit = 100;

Assignment statement

Assignment statement also can use to the user defined data type such as array of character (string copy – strcpy)

Purpose – to copy the content from one string variable to other string variable (and make sure the size of the variable are same)

Format:

strcpy (new_variable_name,old_variable_name)

Example:

char old[20], new[20];

strcpy (new, old)

Function Call statement

Function call statement- used to execute the statement in a particular function.

Purpose : The result of calling a function and supplying the values for the function parameters.

Format :function_name( expression1, expression2,…

expressionn);Example:

cout << calculatepower( ); // with output statement

cout<<pow ( z+y, n); / /with parameter

value =sqrt(x);total = calculate ( x, y ); // with assignment statement

Expression Concepts

Programmers should know how to construct the expression and how to get the value.

The expression should syntactically correct and meaningful combination of operators and operand.

Type of expression

Regular expressionArithmetic expressionLogical Expression (discuss in chapter 3)

Regular expression – describing numbers and denotes any digit

between 0 – 9.

Example : x = 20;

Arithmetic Expression

Arithmetic expression – using arithmetic operator such as +, -, / etc

Example :

sum = no1 + no2

total = (no1 – 10) + ( no3 – 20)

C++ Operation

Arithmetic Operator

Algebraic expression C++ expression

Addition + F + 5 F + 5

Subtraction - P - C P - C

Multiplication x B x M P * M

Division / X / Y or X ÷ Y X / Y

Modulus % R mod S R % S

Modulus - operator must applied to integer only give the remainder of the integer division

Arithmetic Expression (cont.)

Operator Operation Order of evaluation

( ) Parentheses Evaluated first, left to right

*, /, or % MultiplicationDivisionModulus

Evaluated last, if there are several, left to right.

+ or - AdditionSubtraction

Evaluated last, if there are several, left to right.

Precedence of arithmetic operators


Sequence structure – the computer executes C++ statements one after the other in order in which they are written.


Output StatementInput Statement Process Statement

Assignmentstatement

Function Call Statement

chapter 2 basic element of programming

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