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I tried compiling with or without the inclusion guards in C headers and made sure that multiple c files includes the same header. It would result to redeclaration and it is allowed. What does it for then?

Xegara
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1 Answers1

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You prevent circular inclusion:

Example

/** file A.h */
#include "B.h"

/** file B.h */
#include "A.h"

What will happen if you include either "A.h" or "B.h"? Your pre-processor will try to include the other file, which will include the other file, which will include the other file, …

Guards make sure that you won't include the file several times.

Zeta
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  • Would it cause a compiler error if that's the case? Because I just tried it in dev cpp and it still did compile. – Xegara Nov 10 '13 at 16:38