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Re: (un)signed warning

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בתאריך יום חמישי, 26 באפריל 2012 15:45:16 UTC+1, מאת Guillaume Dargaud:
> 
> int n, RL;
> 
> n=RL=GpsResponseLength()-4;
> n+=4;
> 	
> else if (n<RL) printf("Reply too short");
>
n must always be larget than RL, unless an arithemtic overflow occurs. Since n and Rl are signed, this generates undefined behaviour (the program could crash out with an arithemtic overflow message, or it could set N to a very high negative number, or, as in this case, it could simply optimise out the comparison to RL and assume that n is bigger than it). The compiler is warning you that it has taken the last option, which might not be what you want, since the redundant test might well be a erroneous test for overflow. It can't read your mind.
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(un)signed warning Guillaume Dargaud <use_the_contact_form@www.gdargaud.net> - 2012-04-26 11:17 +0200
  Re: (un)signed warning James Kuyper <jameskuyper@verizon.net> - 2012-04-26 06:47 -0400
    Re: (un)signed warning Guillaume Dargaud <use_the_contact_form@www.gdargaud.net> - 2012-04-26 16:45 +0200
      Re: (un)signed warning James Kuyper <jameskuyper@verizon.net> - 2012-04-26 11:39 -0400
      Re: (un)signed warning Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-04-26 09:35 -0700
        Re: (un)signed warning Fred K <fred.l.kleinschmidt@gmail.com> - 2012-04-26 11:19 -0700
          Re: (un)signed warning ImpalerCore <jadill33@gmail.com> - 2012-04-26 12:01 -0700
          Re: (un)signed warning Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-04-28 04:23 -0700

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