C preprocessor?

The C programming language supports preprocessors in order to work the program efficiently. C preprocessor is a macro preprocessor for C-based programming languages. The preprocessor provides the compiler with the ability to include header files, macro expansion, conditional compilation, and line control in an explicit manner.

#hash tag is used to define preprocessors, that is, all preprocessors start with #. This is followed by the name of the preprocessor without any spaces. Here is a list of C preprocessors.

S.No.	Preprocessor	Description
1.	#include	Include specific header files from a file.
2.	#define	Define preprocessor macros.
3.	#undef	Undefine preprocessor macro
4.	#if	Checks the compile-time condition and evaluates to True value.
5.	#else	Evaluate as an alternative to if preprocessor .
6.	#ifndef	Checks whether the macro is defined. If undefined, evaluates to TRUE .
7.	#elif	Simultaneously combine #if and #else statements.
8.	#error	Defined by stderr method Printed error message.
9.	#endif	End preprocessor condition.
10.	#pragma	Used to issue commands to the compiler/

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