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Compiler Warning (level 1) C4293

Error Message

'operator' : shift count negative or too big, undefined behavior

If a shift count is negative or too large, the behavior of the resulting image is undefined.


The following sample generates C4293:

// C4293.cpp
// compile with: /c /W1
unsigned __int64 combine (unsigned lo, unsigned hi) {

   return (hi << 32) | lo;   // C4293

   // try the following line instead
   // return ( (unsigned __int64)hi << 32) | lo;