checking for overflow in C

[Jeffrey Shallit]

Fans of C frequently boast that it is "very close to the machine".  Since
I'm a relative newcomer to the language, perhaps someone could enlighten
me about the officially approved way of checking overflow when multiplying
two integers.  Or is doing (i) a pre-multiply test to ensure the arguments
aren't too big or (ii) a post-division step to ensure the accuracy of the
result the only portable way of doing this?

Jeff Shallit
shallit at dartmouth.edu