Math.Truncate() Method in C#

The Math.Truncate() method in C# is used to remove the fractional part of a number and return only the integral part. It works with both decimal and double data types, effectively cutting off all digits after the decimal point without rounding.

Syntax

The Math.Truncate() method has two overloads −

public static decimal Truncate(decimal d)
public static double Truncate(double d)

Parameters

• d − A decimal or double number to truncate.

Return Value

Returns the integral part of the specified number. The return type matches the input parameter type (decimal returns decimal, double returns double).

Using Math.Truncate() with Decimal Values

Example

using System;

public class Demo {
   public static void Main() {
      decimal val1 = 25.46467m;
      decimal val2 = 45.9989m;
      decimal val3 = 678.325m;
      decimal val4 = -12.789m;
      
      Console.WriteLine("Original: " + val1 + " -> Truncated: " + Math.Truncate(val1));
      Console.WriteLine("Original: " + val2 + " -> Truncated: " + Math.Truncate(val2));
      Console.WriteLine("Original: " + val3 + " -> Truncated: " + Math.Truncate(val3));
      Console.WriteLine("Original: " + val4 + " -> Truncated: " + Math.Truncate(val4));
   }
}

The output of the above code is −

Original: 25.46467 -> Truncated: 25
Original: 45.9989 -> Truncated: 45
Original: 678.325 -> Truncated: 678
Original: -12.789 -> Truncated: -12

Using Math.Truncate() with Double Values

Example

using System;

public class Demo {
   public static void Main() {
      double val1 = 95.86467;
      double val2 = 25.11;
      double val3 = 878.325;
      double val4 = -56.999;
      
      Console.WriteLine("Original: " + val1 + " -> Truncated: " + Math.Truncate(val1));
      Console.WriteLine("Original: " + val2 + " -> Truncated: " + Math.Truncate(val2));
      Console.WriteLine("Original: " + val3 + " -> Truncated: " + Math.Truncate(val3));
      Console.WriteLine("Original: " + val4 + " -> Truncated: " + Math.Truncate(val4));
   }
}

The output of the above code is −

Original: 95.86467 -> Truncated: 95
Original: 25.11 -> Truncated: 25
Original: 878.325 -> Truncated: 878
Original: -56.999 -> Truncated: -56

Comparison with Other Methods

Conclusion

The Math.Truncate() method simply removes the fractional part of a number without performing any rounding. Unlike Math.Floor() or Math.Ceiling(), it always moves toward zero, making it useful when you need the integral part regardless of the number's sign.