totn C Language

C Language: #else Directive

This C tutorial explains how to use the #else preprocessor directive in the C language.

Description

In the C Programming Language, the #else directive provides an alternate action when used with the #if, #ifdef, or #ifndef directives. The preprocessor will include the C source code that follows the #else statement when the condition for the #if, #ifdef, or #ifndef directive evaluates to false.

Syntax

The syntax for the #else directive in the C language is:

#else

Note

Example

The following example shows how to use the #else directive in the C language:

/* Example using #else directive by TechOnTheNet.com */

#include <stdio.h>

#define YEARS_OLD 12

int main()
{
   #if YEARS_OLD < 10
   printf("TechOnTheNet is a great resource.\n");
   #else
   printf("TechOnTheNet is over %d years old.\n", YEARS_OLD);
   #endif

   return 0;
}

Here is the output of the executable program:

TechOnTheNet is over 12 years old.