C# .Truncate()

The Math.Truncate() method in C# returns the integer part of a specified number by removing any fractional digits. It works with both decimal and double types.

Syntax

Math.Truncate(double d)

Or, alternatively:

Math.Truncate(decimal d)

Parameters:

• d (double | decimal): The number whose fractional part is to be discarded.

Return value:

• Returns a double if a double is passed and a decimal if a decimal is passed.
• Special values like NaN, PositiveInfinity, and NegativeInfinity are returned as-is.

Note: Math.Truncate() always rounds towards zero. This means Math.Truncate(2.8) is 2, and Math.Truncate(-2.8) is -2. This is different from Math.Floor(), which always rounds down (e.g., Math.Floor(-2.8) would be -3).

Example 1: Using double

In this example, a double value is truncated to its integer part:

using System;

public class Example {
  public static void Main() {
    double positiveValue = 12.9;
    double negativeValue = -4.7;

    Console.WriteLine("Truncating " + positiveValue + " gives: " + Math.Truncate(positiveValue));
    Console.WriteLine("Truncating " + negativeValue + " gives: " + Math.Truncate(negativeValue));
  }
}

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This example results in the following output:

Truncating 12.9 gives: 12
Truncating -4.7 gives: -4

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Example 2: Using decimal

In this example, a decimal value is truncated without using the m suffix by explicitly casting a double to decimal:

using System;

public class Example {
  public static void Main() {
    decimal decValue = (decimal)45.678;
    decimal negDecValue = (decimal)-23.456;

    Console.WriteLine("Truncating decimal " + decValue + " gives: " + Math.Truncate(decValue));
    Console.WriteLine("Truncating decimal " + negDecValue + " gives: " + Math.Truncate(negDecValue));
  }
}

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The output of this code is:

Truncating decimal 45.678 gives: 45
Truncating decimal -23.456 gives: -23

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Codebyte Example

In this example, both double and decimal values are truncated in a small array of numbers:

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