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Double.ToString Method (String)

Updated: October 2008

Converts the numeric value of this instance to its equivalent string representation, using the specified format.

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

public string ToString(
	string format


Type: System.String

A numeric format string (see Remarks).

Return Value

Type: System.String
The string representation of the value of this instance as specified by format.


format is invalid.

The return value can be PositiveInfinitySymbol, NegativeInfinitySymbol, NaNSymbol, or the string representation of a number, as specified by format.

The format parameter can be any valid standard numeric format specifier except for D and X, as well as any combination of custom numeric format specifiers. If format is null or an empty string, the return value is formatted with the general numeric format specifier ("G").

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

The return value is formatted using the NumberFormatInfo object for the current culture. To apply the formatting conventions of a specified culture, call the Double.ToString(String, IFormatProvider) method.

By default, the return value only contains 15 digits of precision although a maximum of 17 digits is maintained internally. If the value of this instance has greater than 15 digits, ToString returns PositiveInfinitySymbol or NegativeInfinitySymbol instead of the expected number. If you require more precision, specify format with the "G17" format specification, which always returns 17 digits of precision, or "R", which returns 15 digits if the number can be represented with that precision or 17 digits if the number can only be represented with maximum precision.

The return value is formatted with NumberFormatInfo data for the current culture.

The following example displays several Double values using each of the supported standard numeric format specifiers together with two custom numeric format strings. One of those custom format strings illustrates how to pad a Single value with leading zeroes. In converting the numeric values to strings, the example uses the formatting conventions of the en-US culture.

double[] numbers= {1054.32179, -195489100.8377, 1.0437E21, 
string[] specifiers = { "C", "E", "e", "F", "G", "N", "P", 
                        "R", "#,000.000", "0.###E-000",
                        "000,000,000,000.00###" };
foreach (double number in numbers)
   Console.WriteLine("Formatting of {0}:", number);
   foreach (string specifier in specifiers)
      Console.WriteLine("   {0,5}: {1}", 
                        specifier, number.ToString(specifier));

// The example displays the following output to the console: 
//       Formatting of 1054.32179: 
//              C: $1,054.32 
//              E: 1.054322E+003 
//              e: 1.054322e+003 
//              F: 1054.32 
//              G: 1054.32179 
//              N: 1,054.32 
//              P: 105,432.18 % 
//              R: 1054.32179 
//          #,000.000: 1,054.322 
//          0.###E-000: 1.054E003 
//          000,000,000,000.00###: 000,000,001,054.322 
//       Formatting of -195489100.8377: 
//              C: ($195,489,100.84) 
//              E: -1.954891E+008 
//              e: -1.954891e+008 
//              F: -195489100.84 
//              G: -195489100.8377 
//              N: -195,489,100.84 
//              P: -19,548,910,083.77 % 
//              R: -195489100.8377 
//          #,000.000: -195,489,100.838 
//          0.###E-000: -1.955E008 
//          000,000,000,000.00###: -000,195,489,100.00 
//       Formatting of 1.0437E+21: 
//              C: $1,043,700,000,000,000,000,000.00 
//              E: 1.043700E+021 
//              e: 1.043700e+021 
//              F: 1043700000000000000000.00 
//              G: 1.0437E+21 
//              N: 1,043,700,000,000,000,000,000.00 
//              P: 104,370,000,000,000,000,000,000.00 % 
//              R: 1.0437E+21 
//          #,000.000: 1,043,700,000,000,000,000,000.000 
//          0.###E-000: 1.044E021 
//          000,000,000,000.00###: 1,043,700,000,000,000,000,000.00 
//       Formatting of -1.0573E-05: 
//              C: $0.00 
//              E: -1.057300E-005 
//              e: -1.057300e-005 
//              F: 0.00 
//              G: -1.0573E-05 
//              N: 0.00 
//              P: 0.00 % 
//              R: -1.0573E-05 
//          #,000.000: 000.000 
//          000,000,000,000.00###: -000,000,000,000.00001 

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0




October 2008

Added code to the example to pad a Double value with leading zeroes.

Customer feedback.