C Preprocessor Directives

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C Preprocessor Directives:

The Preprocessor Directives are a part of C program which are executed before compilation, hence the name Preprocessor. These Preprocessor Directives are easily identified as they starts with hash # symbol. The preprocessors are also used to add macros in a C program.

Some of the Preprocessor Directives are;

  • #include
  • #define
  • #undef
  • #ifdef
  • #ifndef
  • #if
  • #else
  • #elif
  • #endif
  • #error
  • #pragma

 

Example:

#include <stdio.h>  
void main()
{  
printf("Hello C.");  
}

Output

Hello C.