Include guard style, C++

Question

I have a .h file which contains several class definitions. I'd like to use C++'s include guards in this file; however, I was wondering which way of using the include guards is considered proper/correct?

One guard protecting everything

#ifndef FOO_BAR
#define FOO_BAR

class Foo
{
};

class Bar
{      
};

#endif

or multiple separate guards.

#ifndef FOO
#define FOO

class Foo
{
};

#endif

#ifndef BAR
#define BAR

class Bar
{      
};

#endif

One is enough. Both classes should only be defined once, which happens to anything inside the guard. — chris, Sep 08 '12 at 00:32

score 5 · Accepted Answer · answered Sep 08 '12 at 00:34

5

They are include guards, preventing double inclusion of files. So they should be defined once per file, not per class or function or whatever.

answered Sep 08 '12 at 00:34

Jost

5,992
8
37
65

score 2 · Answer 2 · edited May 23 '17 at 12:27

2

Have you considered to use #pragma once ? Most modern compilers support it.

Is #pragma once a safe include guard?

edited May 23 '17 at 12:27

Community

1
1

answered Sep 08 '12 at 02:10

tzuchien.chiu

690
6
11

Include guard style, C++

2 Answers2

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