Export (0) Print
Expand All

Math.Round Method (Double, MidpointRounding)

Rounds a double-precision floating-point value to the nearest integer. A parameter specifies how to round the value if it is midway between two numbers.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public static double Round(
	double value,
	MidpointRounding mode
)

Parameters

value
Type: System.Double

A double-precision floating-point number to be rounded.

mode
Type: System.MidpointRounding

Specification for how to round value if it is midway between two other numbers.

Return Value

Type: System.Double
The integer nearest value. If value is halfway between two integers, one of which is even and the other odd, then mode determines which of the two is returned.

ExceptionCondition
ArgumentException

mode is not a valid value of System.MidpointRounding.

NoteNote

For examples and comprehensive usage information about this and other overloads of the Round method, see the Round reference page.

Notes to Callers

Because of the loss of precision that can result from representing decimal values as floating-point numbers or performing arithmetic operations on floating-point values, in some cases the Round(Double, MidpointRounding) method may not appear to round midpoint values to the nearest even integer. In the following example, because the floating-point value .1 has no finite binary representation, the first call to the Round(Double) method with a value of 11.5 returns 11 instead of 12.

using System;

public class Example
{
   public static void Main()
   {
      double value = 11.1;
      for (int ctr = 0; ctr <= 5; ctr++)    
         value = RoundValueAndAdd(value);

      Console.WriteLine();

      value = 11.5;
      RoundValueAndAdd(value);
   }

   private static double RoundValueAndAdd(double value)
   {
      Console.WriteLine("{0} --> {1}", value, Math.Round(value, 
                        MidpointRounding.AwayFromZero));
      return value + .1;
   }
}
// The example displays the following output: 
//       11.1 --> 11 
//       11.2 --> 11 
//       11.3 --> 11 
//       11.4 --> 11 
//       11.5 --> 11 
//       11.6 --> 12 
//        
//       11.5 --> 12

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Was this page helpful?
(1500 characters remaining)
Thank you for your feedback
Show:
© 2014 Microsoft