How to multiply two ints and check

[Tim McDaniel]

In article <4700038 at m.cs.uiuc.edu> robison at m.cs.uiuc.edu writes:
>There is a much simpler, faster, and machine-independent way to check
>for multiplication overflow --- check the product by division.  To wit:
...
>			int product = n1*n2;
>			if( n2!=0 && product/n2 != n1 )

(1) The overflow happens before the check.  Bad news if your program
is aborted unrecoverably on overflow.
(2) Divide can overflow.  Consider INT_MIN/-1 on a 2s-complement
machine.

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