Casting double to ulong weirdness

[via Digitalmars-d]

On Monday, 24 August 2015 at 22:12:42 UTC, H. S. Teoh wrote:
> On Mon, Aug 24, 2015 at 09:34:22PM +0000, via Digitalmars-d 
> wrote: [...]
>> What is the correct way to truncate, not round, a 
>> floating-point value to an integer?
>
> std.math.trunc.
>
>
> T

import std.stdio;
import std.math;

void main() {
	double x = 1.2;
	writeln(std.math.trunc(x * 10.0));

	double y = x * 10.0;
	writeln(std.math.trunc(y));
}

Outputs:
11
12