PROGRAMMING LANGUAGE

Lecture #7

CONTROL STRUCTURE & FLOW CHARTS

ByShahid Naseem

(Lecturer)

LECTURE OUTLINES

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LECTURE OUTLINESIF Statement & Flow ChartIF-ELSE statement & Flow ChartThe “NESTED IF” Statement & Flow ChartThe “NESTED IF-ELSE” statement & Flow

ChartThe “SWITCH” StatementThe “BREAK” StatementDifference between “nested if-else” &

“Switch” Statements.The “goto” Statement.

Control Structure (Civil Engineering Department)

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THE “IF” STATEMENT

Control Structure (Civil Engineering Department)

The “IF” statement is used to execute a set of statements after testing a condition.

The “IF” statement evaluates a condition , if the given condition is true, the statement following the “if statement” is executed.

If the condition is false, the statement following the “if statement” condition is ignored and the control transfers to the next statement.

Syntax if(condition)

statement-1;statement-2;

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THE “IF” STATEMENT

Control Structure (Civil Engineering Department)

Set of statements

Statements after if

structure

TRUEFALSE

CONDITION

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THE “IF” STATEMENT

Control Structure (Civil Engineering Department)

Write a program to input a number. If the number is divisible by 3 then print the message on the screen that the number is divisible by 3. Use “IF statement”.#include<iostream.h>void main(){

int n;cout<<“enter a number?”;cin>>n;if(n%3==0){ cout<<“the number”<<“is divisible

by 3”;}

}

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ASSIGNMENT #2

Control Structure (Civil Engineering Department)

Write a program to calculate the electricity bill. The rates of electricity per units are as follow.1. If the units consumed are equal or less than 300, then the cost is Rs. 3/- per unit.

2. If the units consumed are more than 300, then the cost is Rs.3.5/- per unit and a surcharge of 5% of bill is added.

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THE “IF-ELSE STATEMENT

Control Structure (Civil Engineering Department)

The “IF-ELSE statement” is used for making two-way decisions. In this statement, one condition and two blocks of statements are given. Either one of the two blocks of statements is executed after evaluating a condition.

The “IF-ELSE” statement tests the given relational condition.

If the condition is true then the first block of statements is executed else the other statements if the condition is false.

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THE “IF-ELSE STATEMENT

Control Structure (Civil Engineering Department)

Syntaxif (condition){

statement-1;statement-2;--------------statement-n; }

else { statement-1;

statement-2; }

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THE “IF-ELSE” STATEMENT

Control Structure (Civil Engineering Department)

Block-1

Statements after if

structure

TRUEFALSE

CONDITION

Block-2

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THE “IF-ELSE STATEMENT

Control Structure (Civil Engineering Department)

Write a program to input a number from the keyboard. Use IF-ELSE statement to find out whether the number is less than or greater than 100.

#include<iostream.h>void main (){

int n;cout<<“enter an integer value?”;cin>>n;

if (n>100)cout<<“number is greater than

100”;else

cout<<“number is less than 100”;}

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ASSIGNMENT #3

Control Structure (Civil Engineering Department)

Write a program to calculate the “NET PAY” of an employee. Input the basic pay and calculate the “NET PAY” and calculate the NET PAY as follows.

House Rent is 45% of the basic pay.Medical allowance is 2% of basic if basic

is greater than Rs. 5000. It is 5% of basic pay if the pay is less than Rs.5000.

Conveyance allowance is Rs.96/- if basic pay is less than Rs. 5000. It is Rs.193/- if the basic pay is more than Rs.5000/-

Net Pay is calculated by adding basic pay, medical allowance, conveyance allowance and house rent.

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THE “NESTED-IF” STATEMENT

Control Structure (Civil Engineering Department)

When an “IF statement” is used within another “IF statement”, it is called the “nested if statement”.

The “nested if statement” is used for multi-way decision making.

Syntaxif (condition){

if (condition){

statement-1;}statement-2;

}

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THE “NESTED-IF” STATEMENT

Control Structure (Civil Engineering Department)

Block-1

Next Statement

TRUEFALSE

CONDITION-1

Block-2

FALSETRUE

CONDITION-2

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THE “NESTED-IF” STATEMENT

Control Structure (Civil Engineering Department)

Write a program to input three integer values. Compare the three values to find out if they are equal. Use “Nested if statement” and print the message “ all values are equal” if they are equal. Otherwise print the message “These values are Different”.

#include<iostream.h>Void main (){

int a,b,c;cout<<“enter first integer?”;cin>>a;

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THE “NESTED-IF” STATEMENT

Control Structure (Civil Engineering Department)

cout<<“enter second integer?”;cin>>b;cout<<“enter third integer?”;cin>>c;

if(a==b ){

if(a==c)cout<<“All values are equal”;

}elsecout<<“These values are different”;

}

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THE “NESTED-IF-ELSE” STATEMENT

Control Structure (Civil Engineering Department)

When an “if-else” structure is placed in another “if-else “structure, it is called “nested-if-else” structure. It is used for multiple selection.

Syntaxif (condition-1)statement-1;else if (condition-2)statement-2;elsestatement-3;

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THE “NESTED-IF-ELSE” STATEMENT

Control Structure (Civil Engineering Department)

Block-1

Statement after if-else structure

TRUE

FALSE

CONDITION-1

Block-2

FALSE

TRUE

CONDITION-2

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THE “NESTED-IF-ELSE” STATEMENT

Control Structure (Civil Engineering Department)

Write a program to perform simple arithmetic operation by using “nested –if-else” structure.

#include<iostream.h>Void main (){

int a,b;char op;cout<<“enter first integer, operator & second integer/n ”;cout<<“press enter key”;cin>>a>>op>>b;

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THE “NESTED-IF-ELSE” STATEMENT

Control Structure (Civil Engineering Department)

If (op==‘+’)cout<<“Addition=“<<(a+b);

Elseif (op==‘-’)cout<<“Subtraction=“<<(a-b);

Elseif (op==‘*’)cout<<“Multiplication=“<<(a*b);

Else if (op=‘/’)cout<<“Division=“<<(a/b);

Else if (op=‘%’)cout<<“Remainder=“<<(a%b);

Elsecout<<“Invalid input”; }

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THE “SWITCH” STATEMENT

Control Structure (Civil Engineering Department)

The “Switch” statement, is used as a substitute of “Nested-if-else statements”.

It is used when multiple choices are given and one choice is to be selected.

The “nested-if-else” structure becomes complicated in multiple choices.

The “Switch Statement” is used in such situations.

Only one condition is given in the “switch statement” and multiple choices are given inside the main body.

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THE “SWITCH” STATEMENT

Control Structure (Civil Engineering Department)

Syntaxswitch (expression)

{case const-1:

statements;break;case const-2:

statements;break;default:

statement; }

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THE “SWITCH” STATEMENT

Control Structure (Civil Engineering Department)

Write a program to input an integer value. Test the integer value if the value is divisible by 2, then print the message “Divisible by 2” otherwise “Not divisible by 2” by using switch statement.

#include<iostream.h>Void main (){

int n;cout<<“enter any value”<<endl;cin>>n;

Switch(n%2)

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THE “SWITCH” STATEMENT

Control Structure (Civil Engineering Department)

{Case o:

cout<<“Divisible by 2”<<endl;Break;case 1:

cout<<“Not divisible by 2”<<endl;Break;}Cout<<“ok”<<endl;}

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THE “BREAK” STATEMENT

Control Structure (Civil Engineering Department)

The “BREAK” statement is used to exit from the body of the switch structure.

In the switch statement, the break statement is normally used at the end of statements in each case.

It exits the control from the body of switch structure.

If it is not used then the statements of other cases that come after the matching case will also be exectued.

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ASSIGNMENT #4

Control Structure (Civil Engineering Department)

Write a program to perform simple arithmetic operation by using SWITCH STATEMENT

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DIFFERENCE B/W “NESTED-IF-ELSE” AND “SWITCH” STATEMENTS

Control Structure (Civil Engineering Department)

NESTED IF-ELSE STATEMENT

SWITCH STATEMENT

i. It becomes complicated for multiple selections.

It is easy to understand for multiple selections.

ii. It uses an independent expression for each case.

It uses a single expression for all cases, but each case must have a constant value of integer type or character type.

iii. The test condition can be given in a special range of value. If the given condition matches then the statements under it will be executed.

Only a single expression is given in the switch statement which returns a single value. The test condition cannot be given in a specified range. It is drawback.