syspath_once

Controls how included files are treated when #pragmaonce is enabled.

Syntax

  #pragma syspath_once on | off | reset

Remarks

When this pragma and pragma once are set to on, the compiler distinguishes between identically-named header files referred to in #include <file-name> and #include "file-name".

When this pragma is off and pragma once is on, the compiler will ignore a file that uses a

  #include <file-name>

directive if it has previously encountered another directive of the form

  #include "file-name"

for an identically-named header file.

The following listing shows an example.

This pragma does not correspond to any panel setting. By default, this setting is on.

Listing: Pragma syspath_once example

#pragma syspath_once off 
#pragma once on /* Include all subsequent files only once. */ 
#include "sock.h" 
#include <sock.h> /* Skipped because syspath_once is off. */