There are two ways to tell QuickC where to search for an include file. You may have noticed that the #include directive shown earlier encloses the filename STDIO.H in angle brackets (<>). If you enclose the filename in angle brackets, as in the directive
#include <stdio.h>
the compiler searches the “standard directories” for the file.
In QuickC, the standard directories are one or more directories that you define by a DOS environment variable named INCLUDE. An advantage of specifying the standard directories is that QuickC can automatically search more than one directory.
Alternatively, you can enclose the filename in double quotes, in the following manner,
#include “myfile.h”
to cause QuickC to start searching in the directory that contains the current source file. If the target file isn't in that directory, the compiler searches the standard directories.