What does include in C language do?

#include in C language is used to include other source files into the current source file. Uses include code reuse, header inclusion, and modular development. The syntax is #include <header_file> (standard library header file) or #include "header_file" (custom header file).

include in C language

In C language, #includepreprocessing Directive is used to include other source files into the current source file. It is essentially a copy operation that inserts all the contents of the included file into the precompiler directive in the file that contains it.

Usage

#include is mainly used in the following aspects:

• Code reuse :Allows commonly used code blocks or functions to be moved to separate source files for reuse in multiple source files, thereby improving code maintainability and readability.
• Header file contains: Prototypes and constant definitions of standard library functions are usually stored in header files. Use #include to include these header files into source files. , to access and use declared functions and constants.
• Modular development: By organizing code into modules or units that contain specific functionality, #includeallows for modular development, which helps manage large projects and Improve testability.

Syntax

#includeThe syntax of the directive is as follows:

<code>#include <header_file></code>

or:

<code>#include "header_file"</code>

• <header_file> indicates the standard library header file to be included, which is located in the system directory.
• "header_file"Indicates the custom header file to be included, which is located in the current project directory or include path.

Example

Contains a custom header file named my_header.h:

<code class="c">#include "my_header.h"</code>

containsstdio.hStandard library header file, which contains the prototypes of standard input/output functions:

<code class="c">#include <stdio.h></code>

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