Test if a floating point number is an integer

c# floating-point numerical
BCS picture BCS · Sep 27, 2008 · Viewed 16.1k times · Source

This code works (C# 3)

double d;
if(d == (double)(int)d) ...;
  1. Is there a better way to do this?
  2. For extraneous reasons I want to avoid the double cast so; what nice ways exist other than this? (even if they aren't as good)

Note: Several people pointed out the (important) point that == is often problematic regrading floating point. In this cases I expect values in the range of 0 to a few hundred and they are supposed to be integers (non ints are errors) so if those points "shouldn't" be an issue for me.

Answer

Mike F picture Mike F · Sep 27, 2008 
d == Math.Floor(d)

does the same thing in other words.

NB: Hopefully you're aware that you have to be very careful when doing this kind of thing; floats/doubles will very easily accumulate miniscule errors that make exact comparisons (like this one) fail for no obvious reason.

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