Name
#include
Synopsis
The #include
directive
instructs the preprocessor to insert the contents of a specified file
in the program at the point where the #include
directive appears.
Syntax:
#include <filename
> #include "filename
"
If the filename is enclosed in angle brackets, the preprocessor only
searches for it in certain directories. These directories are usually
named in the environment variable
INCLUDE
.
If the filename is enclosed in quotation marks, the preprocessor first looks for the file in the current working directory.
The filename
may contain a directory path.
In this case, the file is only looked for in the specified directory.
The files named in include directives are
generally “header” files containing
declarations and macro definitions for use in several source files,
and have names ending in .h. Such files may in
turn contain further #include
directives.
In the following example, one file to be included is selected based on the value of a symbolic constant:
#include <stdio.h> #include "project.h"
#if VERSION == 1 #define MYPROJ_H "version1.h" #else #define MYPROJ_H "version2.h" #endif
#include MYPROJ_H
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