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Editorial Team
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Asked: 2026-05-24T06:38:06+00:00

The code review tool I use complains with the below when I start comparing

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The code review tool I use complains with the below when I start comparing two float values using equality operator. What is the correct way and how to do it? Is there a helper function (commons-*) out there which I can reuse?

Description

Cannot compare floating-point values using the equals (==) operator

Explanation

Comparing floating-point values by using either the equality (==) or inequality (!=) operators is not always accurate because of rounding errors.

Recommendation

Compare the two float values to see if they are close in value.

float a;
float b;

if(a==b)
{
..
}
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1 Answer

  1. Editorial Team

    IBM has a recommendation for comparing two floats, using division rather than subtraction – this makes it easier to select an epsilon that works for all ranges of input.

    if (abs(a/b - 1) < epsilon)

    As for the value of epsilon, I would use 5.96e-08 as given in this Wikipedia table, or perhaps 2x that value.

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