Hi Ryan, The compiler correctly deduced that the side-effect of q = 42; is not needed. Making q volatile tells the compiler that the side-effect of q = 42; cannot be determined to not be needed. > By the C99 specification I believe I shouldn't need to use volatile in > this case, but by experimenting with GCC it appears that I do. Based on > my reading, my understanding tells me that GCC is diverging from the > specification here. GCC is compliant with the specification, at least on this issue. > Can someone please explain to me why my understanding is incorrect or > why GCC chooses to diverge? The compiler can fully analyze the use of q, and can determine that q = 42; is a not needed side-effect, since q is not accessed between there and the subsequent q = 7;. HTH, --Eljay
