Why does less than or equal return false for equal numbers?

Question

I have a simple function that returns bool value as a result of comparison of distance between 2 entities to GravityRadius field.

public bool IsEntityPulledByGravity(IEntity entity)
{
    return Vector3.Distance(State.Position, entity.State.Position) <= GravityRadius;
}

Sometimes it works as it suppose to but sometimes it returns incorrect false value. I entered debug mode to analyse it and I can't figure out why it would return false for comparison of 30 <= 30. What am I missing?

score 5 · Accepted Answer · answered Feb 18 '18 at 14:35

5

You shouldn't compare floating point numbers for equality.

This MSDN article specifically describes the situation for System.Single. System.Single.Equals under the section Precision in Comparisons.

answered Feb 18 '18 at 14:35

Paul Mitchell

3,241
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Emmanuel Ogoma · Answer 2 · 2018-02-18T14:49:46.550

1

make sure whatever you are comparing are of the same datatype, you can cast them to same datatype before comparing . Use compareTo in your case since Single class implelements the IComparable interface check this link https://msdn.microsoft.com/en-us/library/system.single(v=vs.110).aspx

edited Feb 18 '18 at 14:49

answered Feb 18 '18 at 14:38

Emmanuel Ogoma

584
5
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Both are of same type `System.Single` check screenshot. – SiD Feb 18 '18 at 14:42
Use comapreTo instead of equality operators – Emmanuel Ogoma Feb 18 '18 at 14:46

Why does less than or equal return false for equal numbers?

2 Answers2