Because properly handling overflow if you're using signed values involves UB, it's super hard to get it right. Even Apple has struggled with it: http://www.sla

Because properly handling overflow if you're using signed values involves UB, it's super hard to get it right. Even Apple has struggled with it: http://www.slashslash.info/2014/02/undefined-behavior-and-apples-secure-coding-guide/ http://www.slashslash.info/2014/02/undefined-behavior-and-ap... If you get it wrong you can also see your program's behavior change with the compiler optimization level, which is incredibly frustrating (and causes a lot of "the compiler is buggy!" beliefs).