5.2 Inclusion of Header Files

The order of the #include directives in any .c file shall be:

/*
 * ... file header ...
 */

#include <config.h>

#include <system-file-1.h>
#include <system-file-2.h>
...
#include <system-file-N.h>

#include <lib-file-1.h>
#include <lib-file-2.h>
...
#include <lib-file-N.h>

Note the empty lines separating the several blocks.

In particular:

• Always include config.h, and do it in the first position.
• Never use the "foo.h" kind of inclusion. Use always <foo.h>.

If some headers shall be included conditionally depending on the host platform, the macros PDF_HOST_* defined in config.h can be used. Those macros are set using autoheader.