Richard Heathfield wrote On 03/09/07 07:37,:

[...]

Unsigned integer types cannot overflow. [...]

This is literally true, but it seems to be a point of

confusion: the matter arises in c.l.c. again and again and

again. Perhaps we need a term to describe the non-overflow-

but-possibly-surprising thing that happens when unsigned

arithmetic operates on an expression whose "mathematical"

value is outside the type's range. "Discontinuity" doesn't

seem appropriate, but "wraparound" (in various forms) has

been used before and seems to convey the right meaning.

Richard's oft-repeated statement might be a little more

informative to the befuddled if it read

Unsigned integer types cannot overflow;

they wrap around.

My own preference would be to focus on the arithmetic

rather than on the type, and say

Unsigned arithmetic cannot overflow; it

wraps around.

.... but that's a minor stylistic point about which reasonable

people can disagree in amity.

(In the post I quoted, Richard goes on to describe

"wrap around" precisely, in terms of modular arithmetic.

That's still helpful, but perhaps "wrap around" would give

the confused reader an up-front handle for understanding.)

Thoughts?

--

Er*********@sun.com