compiler-warning-level-1-c4162.md

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Learn more about: Compiler Warning (level 1) C4162	Compiler Warning (level 1) C4162	11/04/2016	C4162	C4162	21ae3c92-501d-4689-ad7d-13753cb65eff

Compiler Warning (level 1) C4162

'identifier' : no function with C linkage found

A function with C linkage is declared but cannot be found.

To resolve this warning, compile in a .c file (invoke the C compiler). If you must invoke the C++ compiler, place extern "C" before the function declaration.

The following sample generates C4162

// C4162.cpp
// compile with: /c /W1
unsigned char _bittest(long* a, long b);
#pragma intrinsic (_bittest)   // C4162

int main() {
   bool bit;
   long num = 78002;
   bit = _bittest(&num, 5);
}

Possible resolution:

// C4162b.cpp
// compile with: /c
extern "C"
unsigned char _bittest(long* a, long b);
#pragma intrinsic (_bittest)

int main() {
   bool bit;
   long num = 78002;
   bit = _bittest(&num, 5);
}