unless x is an integer larger than 1/2 UINT_MAX... then it's still a bad test.
it's safer to test if the signed is less than 0 otherwise cast that to unsigned. On Sun, Sep 26, 2010 at 10:06 PM, foxmuldrs...@yahoo.com <foxmuldrs...@yahoo.com> wrote: > Use the explicit override if you need signed comparison. > > unsigned int x; > int y; > if ((int)x < y) > > -Rick > > -----Original message----- > > From: J Decker <d3c...@gmail.com> > To: Ian Lance Taylor <i...@google.com> > Cc: gcc@gcc.gnu.org > Sent: Mon, Sep 27, 2010 05:51:56 GMT+00:00 > Subject: Re: signed/unsigned comparison warning level > >> The standards did not leave this open. They define precisely what is >> supposed to happen. >> > Really? I'll have to drop this whole lobbying effort then. That > makes me sad that they didn't define it to be comparing of the numbers > where there are overlaps in signed and unsigned instead of causing all > negative signed values to be wrong. > >> >>> But if it's not fixed, this warning should definatly be issued at >>> default warning level. This should be more like 'if this comparison >>> can be wrong, it will be wrong'. >> >> There is no problem comparing values of signed type with values of >> unsigned type if the signed values are known to be nonnegative. Of >> course it is sometimes hard to know that; hence the warning. But >> enabling the warning by default does not make sense. >> > > It's exactly the fact that 'of course it is sometimes....' that makes > the warning make more sense to be on by default. I don't always know > that I've added an unsigned value to an expression, causing one side > of a comparison to become unsigned, resulting in 100% failure on > negative signed result comparison. > > >> Ian >> >
