Got it! 'extern "C"' needed. I missed that when tracking down the defines and typedefs in WinBase.h.

I hope I chose an appropriate forum. Why does the test code below build in VS2010 as C code but not as C++ code (linker errors further below). And what's needed to make it compile as C++ code. Thanks. - Vince

#include

__declspec(dllimport) int __stdcall SetEnvironmentVariableA(const char *pName, const char *pValue);
__declspec(dllimport) unsigned long __stdcall GetEnvironmentVariableA(const char *pName, char *pValue, unsigned long nSize);

int main ( int argc, char **argv )
{
char szValue[32768];
SetEnvironmentVariableA(argv[1], argv[2]);
GetEnvironmentVariableA(argv[1], szValue, 32768);
return 0;
}

error LNK2001: unresolved external symbol "__declspec(dllimport) unsigned long __stdcall GetEnvironmentVariableA(char const *,char *,unsigned long)" (__imp_?GetEnvironmentVariableA@@YGKPBDPADK@Z)
error LNK2001: unresolved external symbol "__declspec(dllimport) int __stdcall SetEnvironmentVariableA(char const *,char const *)" (__imp_?SetEnvironmentVariableA@@YGHPBD0@Z)