This version omits it: http://en.wikipedia.org/wiki/C_preprocessor#Multiple_evaluation_of_side_effects http://en.wikipedia.org/wiki/C_preprocessor#Multiple_eval

This version omits it: http://en.wikipedia.org/wiki/C_preprocessor#Multiple_evaluation_of_side_effects http://en.wikipedia.org/wiki/C_preprocessor#Multiple_evaluat... It's pretty baffling, what's the point of checking the addresses-of for equality, and then casting it to void without assignment? It's not like it could throw an exception or anything :) The compiler would just optimize it out, so it must be there solely to cause compiler warnings, but I can't figure out any cases that it covers and the final statement does not.