What is function of include in c language?

Answer 1

The #include directive is used to tell the preprocessor that the specified file's contents are to be included at the point where the directive appears, just as if you'd typed those contents in full yourself.

Include files are primarily used to organise declarations of external variables and functions, complex data types, constants and macro definitions. The code need only be declared once, and included wherever required. Think of include files as a means of providing forward declarations without having to retype those declarations in full. The definitions of those declarations needn't be contained in the included file, but they must be made available to the program, either as a linked library or as a separate source code file which includes those same declarations.

The include keyword is used in C to tell the linker what libraries your code is going to be using.

Answer 2

The #include directive means insert the contents of the named file in place of the directive during preprocessing, just as if you'd copy/pasted the entire file by hand. Using the #include directive eliminates duplicate code, eases code maintenance, helps modularise code, ensures consistency and aids readability. Typically, headers contain the declarations and inline function definitions required by the files that include them. Those headers may include other headers, thus a single #include directive may introduce many thousands of lines of code which would otherwise hinder the readability of your code. If anyone really needed to see the code contained in an included header, they can more easily view it in the header itself.

Answer 3

Technically, there isn't one... the compiler itself never sees the "include" directive; it's acted on by the preprocessor. "#include" tells cpp to, um, include another file, as if the contents of that file been typed directly into the file being processed.

Answer 4

It was a Header file in C program which is very useful