Preprocessor Directives

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      In our earlier post we give you knowledge about the Basic Structure of C program. Today we are going to share with you knowledge about the Preprocessor Directives and also tell you its importance in C program.

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• Preprocessor Directives:-

The commands that give instructions to the C compiler are called preprocessor directives. They are given at the beginning of the source code. The preprocessor directives are also known as compiler directives.

                            A preprocessor directive begins with a # sign followed by a word "include" or "define". It is an instruction or directive that tells the C compiler to take action(s) before compiling the source code.

                             The part of the C compiler that takes action on the preprocessor directives is called preprocessor. It does some processing before the actual compilation process starts.

• For Example:-

                                    "include" directives is used to include header file in the C program. This preprocessor directive includes the specified header file into the source code before compiling. It must be noted that preprocessor directive does not end with semicolon (;).

The most important preprocessor directives are:

• include directive
• define directive