Compiler Warning (level 1) C4547 

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Error Message

'operator' : operator before comma has no effect; expected operator with side-effect

The compiler detected an ill-formed comma expression.

This warning is off by default. For more information, see Compiler Warnings That Are Off by Default.

The following sample generates C4547:

// C4547.cpp
// compile with: /W1
#pragma warning (default : 4547)
int i = 0;
int j = 1;
int main() {
   int l = (i != i,0);   // C4547
   // try the following line instead
   // int l = (i != i);
   // or
   // int l = ((void)(i != i),0);
}