C programming language supports preprocessors for efficient working of its program. C Preprocessor is a macro preprocessor for C based programming language. A preprocessor gives the compiler an ability for including header files, macro expansions, conditional compilation and line control in an explicit way.
The # hash tag is used to define a preprocessor i.e. all preprocessors have # in starting. Followed by the name of the preprocessor without any space in between. Here, is a list C preprocessors.
|1.||#include||Includes a specific header from the files.|
|2.||#define||Defines a preprocessor macro.|
|3.||#undef||Undefine a preprocessor macro|
|4.||#if||Checks for a compile time condition and evaluates for True value.|
|5.||#else||Evaluate as alternative of the if preprocessor.|
|6.||#ifndef||Checks if the macros is defined. Evaluates to TRUE if not defined.|
|7.||#elif||Combination of both #if and #else statement.|
|8.||#error||Defines error message print by stderr method.|
|9.||#endif||ends preprocessor condition.|
|10.||#pragma||Used to give commands to compiler/|