signbit question

[Miguel L]

On Thursday, 15 March 2018 at 16:31:56 UTC, Stefan Koch wrote:
> On Thursday, 15 March 2018 at 15:28:16 UTC, Miguel L wrote:
>> Why does std.math.signbit only work for floating point types?
>> Is there an analogue function for integer types? what is the 
>> best way to compare the sign of a float with the sign of an 
>> integer?
>> Thanks in advance
>
> integers don't have a sign-bit.
> since they are not necessarily singed.
> However if an integer is signed and using 1-complement
> you can either do sign = var < 0 or
> sign = (var & (1 << (sizeof(var)*8 - 1));
> though I cannot tell which one is faster you have to experiment.

Thanks. Just one more question:

Is this code correct? I don't care about +0 or -0 as the 
calculations on f guarantee it cannot be 0 at all.

int a;
float f;
....
if((a<0)==signbit(f)) {....}
else {...}