File Inclusion in C

By: Jagan  

File inclusion makes it easy to handle collections of #defines and declarations (among other things). Any source line of the form
   #include "filename"
   #include <filename>
is replaced by the contents of the file filename. If the filename is quoted, searching for the file typically begins where the source program was found; if it is not found there, or if the name is enclosed in < and >, searching follows an implementation-defined rule to find the file. An included file may itself contain #include lines.

There are often several #include lines at the beginning of a source file, to include common #define statements and extern declarations, or to access the function prototype declarations for library functions from headers like <stdio.h>. (Strictly speaking, these need not be files; the details of how headers are accessed are implementation-dependent.)

#include is the preferred way to tie the declarations together for a large program. It guarantees that all the source files will be supplied with the same definitions and variable declarations, and thus eliminates a particularly nasty kind of bug. Naturally, when an included file is changed, all files that depend on it must be recompiled.

Archived Comments

1. my code is unable to open included files
how can it be solved

View Tutorial          By: MANAS at 2013-09-08 05:44:46

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