If - else Statement in C

if else statements are used in C for making decision from one or more conditions.

In this section we will talk about

• Single if Statement
• If else Statement
• Nested if else Statement

Single if Statement

Single if statement is used in C to execute the body( a block of statements ) if the condition is true. The structure of an if statement is given bellow

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if( condition ) {      // This is the body of the if statement. }

Note

• if statement will be executed when the condition is true.
• Between the braces { } is the statement body/block, whatever we write between these braces will be executed if the condition is true.

Let’s look at the following program which will identify either a given number is greater than 0 or not.

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#include <stdio.h>   int main() {     int var;     printf(" Enter a number: ");     scanf(" %d", &var);       if(var > 0)     {         printf(" Given number is greater than 0.");     }     return 0; }

Output

If - else Statement

An if - else statement is used in C to make a decision from a list of condition. The structure of an if - else statement is given bellow

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if( condition1 ) {      // This body statement will be executed when condition1 is true. } else {      // This body statement will be executed when condition1 is false. }

Note

• if statement will be executed if condition1 is true otherwise else statement will be executed.
• Both if and else statement can’t be executed at a time.

Let’s look at the following example

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#include <stdio.h>   int main() {     int num;     printf(" Enter a number: ");     scanf(" %d", &num);       if(num % 2 == 0)     {         printf(" Given number is Even.");     }     else     {         printf(" Given number is Odd.");     }     return 0; }

Sample Output

Sample Output

Note It is not necessary that you have to check only two condition .You can add multiple condition Let’s look into another example

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#include <stdio.h>   int main() {     int var;     printf(" Enter a positive integer : ");     scanf(" %d", &var);         if(var == 1)     {         printf(" Given number is 1.");     }     else if( var == 2)     {         printf(" Given number is 2.");     }     else if( var == 3)     {         printf(" Given number is 3.");     }     else     {         printf(" Given number is greater than 3.");     }       return 0; }

Sample Output

Nested if - else Statement

You can use if - else statement into another if - else statement. Let’s look at the following code.

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#include <stdio.h>   int main() {     int var;     printf(" Enter a positive number : ");     scanf(" %d", &var);         if(var < 10)     {         if(var < = 5)         {             printf(" Given number is less than or equal 5.");         }         else         {             printf(" Given number is greater than 5 and less than 10.");         }     }     else if( var < 20)     {         if(var < = 15)         {             printf(" Given number is less than or equal to 15.");         }         else         {             printf(" Given number is greater than 15 and less than 20.");         }     }     else     {         printf(" Given number is greater than or equal to 20.");     }       return 0; }

Sample Output

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