UInt64.ToString Method (String, IFormatProvider)


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Converts the numeric value of this instance to its equivalent string representation using the specified format and culture-specific format information.

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

public string ToString(
	string format,
	IFormatProvider provider


Type: System.String

A numeric format string.

Type: System.IFormatProvider

An object that supplies culture-specific formatting information about this instance.

Return Value

Type: System.String

The string representation of the value of this instance as specified by format and provider.

Exception Condition

The format parameter is invalid.

The ToString(String, IFormatProvider) method formats a UInt64 value in a specified format by using the NumberFormatInfo object of a specified culture. If you want to use default format or culture settings, use the other overloads of the ToString method, as follows:

To use format

For culture

Use the overload

Default ("G") format

Default (current) culture


Default ("G") format

A specific culture


A specific format

Default (current) culture


The format parameter can be any valid Standard Numeric Format Strings, or any combination of Custom Numeric Format Strings. If format is equal to String.Empty or is null, the return value of the current UInt64 object is formatted with the general format specifier ("G"). If format is any other value, the method throws a FormatException.

The .NET Framework provides extensive formatting support, which is described in greater detail in the following formatting topics:

The provider parameter is an IFormatProvider implementation. Its GetFormat method returns a NumberFormatInfo object that provides culture-specific information about the format of the string returned by this method. When the ToString(String, IFormatProvider) method is invoked, it calls the provider parameter's IFormatProvider.GetFormat method and passes it a Type object that represents the NumberFormatInfo type. The GetFormat method then returns the NumberFormatInfo object that provides information for formatting the current UInt64 value, such as the group separator symbol or the decimal point symbol. There are three ways to use the provider parameter to supply formatting information to the ToString(String, IFormatProvider) method:

  • You can pass a CultureInfo object that represents the culture that supplies formatting information. Its GetFormat method returns the NumberFormatInfo object that provides numeric formatting information for that culture.

  • You can pass the actual NumberFormatInfo object that provides numeric formatting information. (Its implementation of GetFormat just returns itself.)

  • You can pass a custom object that implements IFormatProvider. Its GetFormat method instantiates and returns the NumberFormatInfo object that provides formatting information.

If provider is null, the formatting of the returned string is based on the NumberFormatInfo object of the current culture.

The following example displays a 32-bit unsigned integer value by using the standard numeric format specifiers and a number of specific CultureInfo objects.

using System;
using System.Globalization;

public class Example
   public static void Main()
      // Define cultures whose formatting conventions are to be used.
      CultureInfo[] cultures = { CultureInfo.CreateSpecificCulture("en-US"), 
                                 CultureInfo.CreateSpecificCulture("es-ES") };
      string[] specifiers = {"G", "C", "D4", "E2", "F", "N", "P", "X2"}; 
      ulong value = 22224021;

      foreach (string specifier in specifiers)
         foreach (CultureInfo culture in cultures)
            Console.WriteLine("{0,2} format using {1} culture: {2, 18}",  
                              specifier, culture.Name, 
                              value.ToString(specifier, culture));
// The example displays the following output:
//        G format using en-US culture:           22224021
//        G format using fr-FR culture:           22224021
//        G format using es-ES culture:           22224021
//        C format using en-US culture:     $22,224,021.00
//        C format using fr-FR culture:    22 224 021,00 ?
//        C format using es-ES culture:    22.224.021,00 ?
//       D4 format using en-US culture:           22224021
//       D4 format using fr-FR culture:           22224021
//       D4 format using es-ES culture:           22224021
//       E2 format using en-US culture:          2.22E+007
//       E2 format using fr-FR culture:          2,22E+007
//       E2 format using es-ES culture:          2,22E+007
//        F format using en-US culture:        22224021.00
//        F format using fr-FR culture:        22224021,00
//        F format using es-ES culture:        22224021,00
//        N format using en-US culture:      22,224,021.00
//        N format using fr-FR culture:      22 224 021,00
//        N format using es-ES culture:      22.224.021,00
//        P format using en-US culture: 2,222,402,100.00 %
//        P format using fr-FR culture: 2 222 402 100,00 %
//        P format using es-ES culture: 2.222.402.100,00 %
//       X2 format using en-US culture:            1531C95
//       X2 format using fr-FR culture:            1531C95
//       X2 format using es-ES culture:            1531C95

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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