Linker error when setting variables

[Cmaranec]

Hello again, i have a little problem - i'm woking on simple module manager for my text operating system and linker says that Unresolved external symbol _memset has been found here.

It appears only if i try to do this:

Code: Select all

static moduleinfo modules[MAX_MODULES] = {
	{"Calculator","calc","Calculator v0.1 by Kennny",&modulehandlers::test_calc},
	{"Testing Game","testgam","First Testing Game by Kennny",&modulehandlers::empty_module_handler},
	{"External Module","ext","External module test",&modulehandlers::empty_module_handler},
	{NULL,NULL,NULL,&modulehandlers::empty_module_handler}
};

- if i remove this, linker says nothing and everything (except this) works fine.

Edit: function memset is declared in other file, which is included from there.

Sorry for my bad english.

[Combuster]

Compiler + toolchain? Are you using a GCC Cross-Compiler?

[frank]

Is memset in an assembly file? If it is you might try adding an _ to it. If its not then your going to have to provide some more information about what compiler you are using (DJGPP Cygwin MingW if on Windows) and what OS you are compiling on Windows, Linux?

[Cmaranec]

I'm using MS Visual C++ 2005 to compile. Function memset is in C++ file

[Combuster]

Wouldn't MSVC mangle that name if its defined in C++ context? Try declaring it as extern "C" void memset

[Cmaranec]

Still doesn't work... I don't know why it doesn't appear when i remove my definition (initialization).

[neon]

MSVC does indeed mangle the names if they are defined as C++ symbols.

Anyways, try putting extern void *memset(void*, int, size_t) at the top of your file. If it is still occurring, it is possible that the compiler is calling the intrinsic form of the function instead which can be fixed by putting #pragma function(memset) before you use it.

[Cmaranec]

isn't work... i can't understand, why it appears only if i try to initialize my struct.

Czechian would say "No to mě poser" (don't try to translate)

[frank]

If you understand assembly language then you could try looking at the asm version of what gets compiled. It's under output files in the project settings. Then you could see what its doing with the memset call.

[neon]

I know your declaration of memset has extern C, but also does its definition? (This is important as you are building it as a C++ program)

Also, posting the *exact* error message might be helpful as it should contain the symbolic name that it is trying to call.

[Cmaranec]

Error message:

1>module.obj : error LNK2019: unresolved external symbol _memset referenced in function "void __cdecl `dynamic initializer for 'modules''(void)" (??__Emodules@@YAXXZ)

Function *memset: (string.cpp)

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void *memset(void *dest, char val, size_t count)
{
    unsigned char *temp = (unsigned char *)dest;
	for( ; count != 0; count--, temp[count] = val);
	return dest;
}

extern declaration: (string.h)

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extern void *memset(void *dest, char val, size_t count);

[Combuster]

still C++ linkage rather than C linkage there...

[frank]

extern declaration: (string.h)
Code:
extern void *memset(void *dest, char val, size_t count);

It needs to be

Code: Select all

extern "C" void *memset(void *dest, char val, size_t count);