On 2013-08-29, 10:25, Jonathan M Davis wrote:
On Thursday, August 29, 2013 10:07:31 Paul Jurczak wrote:
On Thursday, 29 August 2013 at 07:51:40 UTC, Jonathan M Davis
wrote:
[..]
> as any integral value in a float will fit in an
> int.
[..]
Will it? Most of them will not fit
Sure, they will. float has 32 bits, just like int, so it can't possibly
hold a
value larger than an int can hold. This code passes with flying colors
foreach(i; int.min .. int.max)
assert(cast(float)i == i);
First, that's showing the exact opposite of what you're saying it does.
Second, it doesn't even show that.
Your code is equivalent to:
foreach(i; int.min .. int.max)
assert(cast(float)i == cast(float)i);
If that does not pass with flying colors, I'd be surprised. Now try this:
foreach(i; int.min .. int.max) {
float f = i; // DMD optimizes out cast(int)cast(float)int
assert(cast(int)f == i);
}
It will fail for odd numbers in the range 16,777,216-33,554,432, and for
numbers not divisible by 4 in the range to the next power of two, then 8,
and so on. These numbers are simply not representable by a float.
For more information:
http://floating-point-gui.de/formats/fp/
--
Simen
