c preprocessor if

by

C #if:

The #if is a preprocessor directive in C which is used to execute a piece of code, only if the specified condition is TRUE.

Syntax:

#if condition

// code to be executed if condition is TRUE.

#endif

OR

#if condition

//  code to be executed if condition is TRUE.

#else

//  code to be executed if condition is FALSE.

#endif

 

Example:

#include<stdio.h>  
#define AGE 30
void main()
{    
#if (AGE==30)
printf("Value of AGE is correct.");
#else  
printf("Wrong value of AGE.");  
#endif    	 
}

Output

Value of AGE is correct.