#else

The #else preprocessor directive evaluates the expression or condition if condition of #if is false. It can be used with #if, #elif, #ifdef and #ifndef directives.

Syntax:

#if expression
//if code
#else
//else code
#endif

 

Syntax with #elif:

#if expression
//if code
#elif expression
//elif code
#else
//else code
#endif

C #else example

Let's see a simple example to use #else preprocessor directive.

#include <stdio.h>
#include <conio.h>
#define NUMBER 1
void main() {
#if NUMBER==0
printf("Value of Number is: %d",NUMBER);
#else
print("Value of Number is non-zero");
#endif
getch();
}

 

Output:

Value of Number is non-zero