C #include

This preprocessor directive is used to spread code of given file into the present file. It is used include system-defined header files. this file is not built, compiler renders error.

It has three variants:

• #include <file>
• #include “file”
• #include anything else

#include <file>

This variant is used for system header files. It searches for a file named file named file in a list of directories specified by you, then in a standard list of system directories.

#include “file”

It is used for header files of the own program. It searches for a file named file first in the current directory, then in the same directories used for system header files and the current directory is the directory of the current input file.

#include anything else

This variant is called a computed #include. Any #include directive which argument does not fit the above two forms is a computed include.

Example:

#include <stdio.h>
void main() {
	printf("Hello World!");
}