Decision making statements

These statements are used to control the flow of execution of a program by making a decision depending on a condition, hence they are named as decision making statements. Decision making statements are of four types.

1. Simple if
2. if else
3. nested if else

1. Simple if Statement

if the test expression is true then if statement executes statements that immediately follow if

Syntax:

``````If(test expression)
{
List of statements;
}``````

Example:

``````#include<stdio.h>
int main()
{
int a,b;
cout<<“Enter any two integers:”;
cin>>a>>b;
if(a>b)
cout<<“A is larger than B\n A=”<<a;
if(b>a)
cout<<“B is larger than A\n A=”<<b;
return 0;
}``````

2. if-else Statement

If test expression is true block of statements following if are executed and if test expression is false then statements in else block are executed.

Syntax:

``````if (test expression)
{
statement block1;
}
else
{
statement block2;
}``````

Example:

``````/*largest of two numbers*/
#include<iostream.h>
int main()
{
int a,b;
cout<<”Enter any two integers:”;
cin>>a>>b;
if(a>b)
cout<<“A is larger than B\n A=”<<a;
else
cout<<“B is larger than A\n A=”<<b;
return 0;
}``````

3. Nesting of if-else statements

It’s also possible to nest one if statement inside another. When a series of decisions are to be made. Simply If –else statement placed inside another if else statement.

Syntax:

``````If(test expression)
{
If(test expression) {
//statements
}
else
{
//statements
}
}
else
{
If(test expression) {
//statements
}
else {
//statements
}
}``````

Example:

``````/*largest of three numbers*/
#include<iostream.h>
#include<conio.h>
int main()
{
int a,b,c;
cout<<"Enter a,b,c values:";
cin>>a>>b>>c;
if(a>b)
{
if(a>c)
{
cout<<"A ia largest among three numbers\n";
cout"A= "<<a;
}
else
{
cout<<"C ia largest among three numbers\n";
cout<<"c= "<<c;
}
}
else
{
if(b>c)
{
cout<<"B ia largest among three numbers\n";
cout<<"B="<<b;
}
else
{
cout<<"C ia largest among three numbers\n";
cout<<"c="<<c;
}
}
getch();
return 0;
}``````

The nesting of if-else depends upon the conditions with which we have to deal. The condition is evaluated from top to bottom.if a condition is true the statement associated with it is executed. When all the conditions become false then final else part containing default statements will be executed.

Syntax:

``````if(condition1)
statement1;
else if(condition2)
statement 2;
else if(condition3)
statement n;
else
default statement.
statement-x;``````

Example:

``````#include<iostream.h>
void main()
{
int per;
cout<<”Enter percentage”;
cin>>per;
if(per>=80)
cout<<”Secured Distinction”<<endl;
else if(per>=60)
cout<<”Secured First Division”<<endl;
else if(per>=50)
cout<<”Secured Second Division”<<endl;
else if(per>=40)
cout<<”Secured Third Division”<<endl;
else
cout<<”Fail”<<endl
}``````