Undefined means that the specification does not define what happens, and that people cannot expect anything, since what happens is implementation dependent.
On Jan 9, 2014, at 8:49 AM, Mattias Engdegård <matti...@bredband.net> wrote: > 9 jan 2014 kl. 14.37 skrev Jim Jagielski: > >> However, if a is 4,294,967,200, then the behavior >> of (int)a is undefined and implementation dependent, >> since you can't express that value within the >> limits of a signed int (assuming 32 bits). > > No, it's not undefined but implementation-defined, which means that an > implementation can decide what to do as long as it documents it. There is > quite a difference. > > All compilers I have ever used, and then some, treat conversions to signed by > modular reduction into the interval defined by that type. Nothing else makes > sense, and compilers won't start doing it differently. > >> My point is that the possibility in that case of >> (int)a resulting in 0 is pretty freakin' remote, >> even if it is undefined behavior ;) > > It's not undefined behaviour. >
