How Can I Accurately Compare Decimal Values in C# When Using Floating-Point Numbers?

Double-precision floating-point number comparison in C#: Precision and accuracy issues

When using double-precision floating-point variables in C#, developers often encounter unexpected results in comparisons involving decimal values. One such problem arises from a fundamental property of floating point representation.

Floating point problem

The

data type in C# uses binary fractions instead of decimal fractions to store floating point values. This representation has its limitations, and some decimal values ​​cannot be stored exactly. For example, the number 0.1 cannot be represented exactly as a binary fraction. It is stored as an approximation, resulting in slightly different values. double

Solution: Decimal type

To overcome this lack of precision, consider using the

data type instead of decimal. double Store numbers using decimal notation, allowing values ​​such as 0.1 to be represented exactly. This eliminates the problems encountered when comparing decimal values. double

Detailed explanation

Floating point numbers are represented using exponent and mantissa, similar to scientific notation. However, instead of using base 10, it uses base 2 (binary notation).

Decimal values ​​such as 0.1 have non-repeating binary representations and are therefore difficult to store accurately in base 2 systems. As a result, the binary approximation of 0.1 stored in the

variable may differ slightly from the actual value. double

This subtle difference can lead to inconsistent comparisons in

statements, where the expected value of 0.1 may not match the stored value. Using the if data type avoids these problems by ensuring accurate storage and comparison of decimal values. decimal

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