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Global function Linking

Started by KodeNerd Jan 12, 2008 at 11:29 PM 4 replies 1k views

Original Post

Jan 12, 2008 at 11:29 PM

When I add this:


#ifndef SEVN_RANDOM
#define SEVN_RANDOM
int Random(int low=0,int high=RAND_MAX) {
	return ((rand()%high+(++low)));
}
#endif

to a .h file and include it (more than once) I always get a multiple definition error when I link...it should not do that. Is there something that I missed?

etsuja

Jan 12, 2008 at 11:39 PM

you're defining the whole definition in the header which won't work...

put this in the header...

int Random(int low=0,int high=RAND_MAX);

and this in the source code.

int Random(int low=0,int high=RAND_MAX) {	return ((rand()%high+(++low)));}

ender7771

Jan 12, 2008 at 11:41 PM

In practice, one should only put a function definition, like

"int Random(int, int);" in a .h, and then the actual code in a .cpp. Try that, and it might fix your problem.

KodeNerd

Jan 13, 2008 at 12:32 AM

Yes that worked. I knew I was missing something stupid (I normally put the definition in a .cpp but didn't for some reason).

fpsgamer

Jan 13, 2008 at 1:46 AM

Quote:
Original post by KodeNerd
When I add this:
*** Source Snippet Removed ***
to a .h file and include it (more than once) I always get a multiple definition error when I link...it should not do that. Is there something that I missed?

If you wish you define a function within a header file it must be declared inline.

inline int Random(int low=0,int high=RAND_MAX) {	return ((rand()%high+(++low)));}

KodeNerd

Jan 13, 2008 at 2:05 AM

That is something I did not know. Thanks.

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