Question

Why does this loop (to 1 billion) only take a few sounds to execute …

for (i = 0; i < 1000000000; i++)
{

}

… but this loop (to 10 billion) takes >10 minutes?

for (i = 0; i < 10000000000; i++)
{

}

Shouldn’t it just take 30 seconds or so (3 seconds x 10)?

Answer 1

I guess i is a 32-bit integer variable and is therefore always smaller than 10 billion (which is more than 2^32), whereas 1 billion still fits into the 32-bit range (which ends at about 2 or 4 billion, depending on signedness). Though I don’t know how the compiler promotes this 10 billion constant, but he seems to realize the overflow issue and makes it an infite loop.

What happens when you make i a long long int (and maybe the 10000000000 a 10000000000L, but that seems to be no problem)?