Can anyone help me understand #pragma?
ifndef TARGET_OS_LINUX
#pragma once
endif
What,when, where, why, an example?
The above is in some code that I am refactoring....
+8
A:
#pragma is just the prefix for a compiler-specific feature.
In this case, #pragma once means that this header file will only ever be included once in a specific destination file. It removes the need for header guards.
John Calsbeek
2009-08-11 23:28:05
etherything is right except warning that #pragmas are compiler extensions, they are not in Standard. You better avoid them.
f0b0s
2009-08-11 23:42:04
isn't that what he said? Compiler-specific feature == non-standard compiler extension
jalf
2009-08-12 00:01:37
@John - So where can I get a list of compiler specific features that I can use? These change depending upon GCC and Intel CC I am sure, so what is the best safe guard for portable code?
2009-08-12 02:50:31
Get the list of compiler specific pragmas? - in your compilers documentation. Best safe guard for portable code? Don't use #pragma.
Richard Corden
2009-08-12 07:59:36
A:
- What -- it is header guard. This file will be included only once.
- When -- at a compile process
- why -- to avoid double including.
"Header guards are little pieces of code that protect the contents of a header file from being included more than once."
f0b0s
2009-08-11 23:44:30