Hi, all I am not sure whether this is a proper place to put up with my question. But I think you can answer my question. See following two clauses int x=20, y=35, z; case 1: x = x++ + y++; case 2: z = x++ + y++; in case 1. the result is x = 36; in case2: the result is z = 35; Whether this is a paradox for post increment operator ? Look forward to your kindly answers. Thanks very much. BRs Zongjun.