checking for overflow in C

[Karl Heuer]

In article <10218 at smoke.BRL.MIL> gwyn at brl.arpa (Doug Gwyn) writes:
>In <13367 at dartvax.Dartmouth.EDU> shallit at eleazar (Jeffrey Shallit) writes:
>>... enlighten me about the officially approved way of checking overflow when
>>multiplying two integers.
>
>How did you get your algorithm into the state where an overflow is
>even possible?

Let's take a concrete example.  How do you think one should code the
implementation of the ANSI C function strtol(), which is required to detect
integer overflow and return ERANGE in this case?

Karl W. Z. Heuer (ima!haddock!karl or karl at haddock.isc.com), The Walking Lint