• bearophile (12/12) Sep 05 2009 This comes from a post from D.learn:

bearophile <bearophileHUGS lycos.com> writes:

This comes from a post from D.learn:
http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D.learn&article_id=17520

This line of code:
const ulong N = 1024 * 1024 * 1024 * 2;

The programmer has not seen N to be 2_147_483_648UL but
18_446_744_071_562_067_968UL.

Steven Schveighoffer has given a good explanation, saying that's "expected and
well-defined behavior".
In truth that's a bug in the code caused by wrongly defined C language specs.
Still, C programmers may expect such weird and unnatural behaviour from the D
compiler too...

D isn't forced to follow C specs. So to solve this bad situation compile-time
overflow checks can be added to D, able to show an overflow warning at
compile-time in such line of code. Such warning can be disabled locally or
globally by people that love the standard C behaviour.

Such compile-time checks give zero penalty at run-time.

Bye,
bearophile