Should I use #include in headers?

Question

Is it necessary to #include some file, if inside a header (*.h), types defined in this file are used?

For instance, if I use GLib and wish to use the

Answer 1

Just include all external headers in one common header file in your project, e.g. global.h and include it in all your c files:

It can look like this:

#ifndef GLOBAL_GUARD
#define GLOBAL_GUARD

#include 
/*...*/
typedef int  YOUR_INT_TYPE;
typedef char YOUR_CHAR_TYPE;
/*...*/
#endif

This file uses include guard to avoid multiple inclusions, illegal multiple definitions, etc.