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Double.ToString Method (String)

.NET Framework 4.5

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
)

Parameters

format: Type: System.String
A numeric format string.

Return Value

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

Exceptions

Exception	Condition
FormatException	format is invalid.

Remarks

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:

For more information about numeric format specifiers, see Standard Numeric Format Strings and Custom Numeric Format Strings.
For more information about formatting, see Formatting Types.

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.

Examples

The following example displays several Double values using the supported standard numeric format specifiers together with three custom numeric format strings. One of those custom format strings illustrates how to pad a Single value with leading zeros. In addition, the example uses precision specifiers with each standard format specifier except for "R". The values of the precision specifiers range from 0 to 3. To convert the numeric values to strings, the example uses the formatting conventions of the en-US culture.

double[] numbers= {1054.32179, -195489100.8377, 1.0437E21, 
                   -1.0573e-05};
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,-22} {1}", 
                        specifier + ":", number.ToString(specifier));
      // Add precision specifiers from 0 to 3. 
      if (specifier.Length == 1 & ! specifier.Equals("R")) {
         for (int precision = 0; precision <= 3; precision++) {
            string pSpecifier = String.Format("{0}{1}", specifier, precision);
            Console.WriteLine("   {0,-22} {1}", 
                              pSpecifier + ":", number.ToString(pSpecifier));
         }    
         Console.WriteLine();
      }   
   }
   Console.WriteLine();
}
// The example displays the following output to the console: 
//       Formatting of 1054.32179: 
//          C:                     $1,054.32 
//          C0:                    $1,054 
//          C1:                    $1,054.3 
//          C2:                    $1,054.32 
//          C3:                    $1,054.322 
//        
//          E:                     1.054322E+003 
//          E0:                    1E+003 
//          E1:                    1.1E+003 
//          E2:                    1.05E+003 
//          E3:                    1.054E+003 
//        
//          e:                     1.054322e+003 
//          e0:                    1e+003 
//          e1:                    1.1e+003 
//          e2:                    1.05e+003 
//          e3:                    1.054e+003 
//        
//          F:                     1054.32 
//          F0:                    1054 
//          F1:                    1054.3 
//          F2:                    1054.32 
//          F3:                    1054.322 
//        
//          G:                     1054.32179 
//          G0:                    1054.32179 
//          G1:                    1E+03 
//          G2:                    1.1E+03 
//          G3:                    1.05E+03 
//        
//          N:                     1,054.32 
//          N0:                    1,054 
//          N1:                    1,054.3 
//          N2:                    1,054.32 
//          N3:                    1,054.322 
//        
//          P:                     105,432.18 % 
//          P0:                    105,432 % 
//          P1:                    105,432.2 % 
//          P2:                    105,432.18 % 
//          P3:                    105,432.179 % 
//        
//          R:                     1054.32179 
//          #,000.000:             1,054.322 
//          0.###E-000:            1.054E003 
//          000,000,000,000.00###: 000,000,001,054.32179 
//        
//       Formatting of -195489100.8377: 
//          C:                     ($195,489,100.84) 
//          C0:                    ($195,489,101) 
//          C1:                    ($195,489,100.8) 
//          C2:                    ($195,489,100.84) 
//          C3:                    ($195,489,100.838) 
//        
//          E:                     -1.954891E+008 
//          E0:                    -2E+008 
//          E1:                    -2.0E+008 
//          E2:                    -1.95E+008 
//          E3:                    -1.955E+008 
//        
//          e:                     -1.954891e+008 
//          e0:                    -2e+008 
//          e1:                    -2.0e+008 
//          e2:                    -1.95e+008 
//          e3:                    -1.955e+008 
//        
//          F:                     -195489100.84 
//          F0:                    -195489101 
//          F1:                    -195489100.8 
//          F2:                    -195489100.84 
//          F3:                    -195489100.838 
//        
//          G:                     -195489100.8377 
//          G0:                    -195489100.8377 
//          G1:                    -2E+08 
//          G2:                    -2E+08 
//          G3:                    -1.95E+08 
//        
//          N:                     -195,489,100.84 
//          N0:                    -195,489,101 
//          N1:                    -195,489,100.8 
//          N2:                    -195,489,100.84 
//          N3:                    -195,489,100.838 
//        
//          P:                     -19,548,910,083.77 % 
//          P0:                    -19,548,910,084 % 
//          P1:                    -19,548,910,083.8 % 
//          P2:                    -19,548,910,083.77 % 
//          P3:                    -19,548,910,083.770 % 
//        
//          R:                     -195489100.8377 
//          #,000.000:             -195,489,100.838 
//          0.###E-000:            -1.955E008 
//          000,000,000,000.00###: -000,195,489,100.8377 
//        
//       Formatting of 1.0437E+21: 
//          C:                     $1,043,700,000,000,000,000,000.00 
//          C0:                    $1,043,700,000,000,000,000,000 
//          C1:                    $1,043,700,000,000,000,000,000.0 
//          C2:                    $1,043,700,000,000,000,000,000.00 
//          C3:                    $1,043,700,000,000,000,000,000.000 
//        
//          E:                     1.043700E+021 
//          E0:                    1E+021 
//          E1:                    1.0E+021 
//          E2:                    1.04E+021 
//          E3:                    1.044E+021 
//        
//          e:                     1.043700e+021 
//          e0:                    1e+021 
//          e1:                    1.0e+021 
//          e2:                    1.04e+021 
//          e3:                    1.044e+021 
//        
//          F:                     1043700000000000000000.00 
//          F0:                    1043700000000000000000 
//          F1:                    1043700000000000000000.0 
//          F2:                    1043700000000000000000.00 
//          F3:                    1043700000000000000000.000 
//        
//          G:                     1.0437E+21 
//          G0:                    1.0437E+21 
//          G1:                    1E+21 
//          G2:                    1E+21 
//          G3:                    1.04E+21 
//        
//          N:                     1,043,700,000,000,000,000,000.00 
//          N0:                    1,043,700,000,000,000,000,000 
//          N1:                    1,043,700,000,000,000,000,000.0 
//          N2:                    1,043,700,000,000,000,000,000.00 
//          N3:                    1,043,700,000,000,000,000,000.000 
//        
//          P:                     104,370,000,000,000,000,000,000.00 % 
//          P0:                    104,370,000,000,000,000,000,000 % 
//          P1:                    104,370,000,000,000,000,000,000.0 % 
//          P2:                    104,370,000,000,000,000,000,000.00 % 
//          P3:                    104,370,000,000,000,000,000,000.000 % 
//        
//          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 
//          C0:                    $0 
//          C1:                    $0.0 
//          C2:                    $0.00 
//          C3:                    $0.000 
//        
//          E:                     -1.057300E-005 
//          E0:                    -1E-005 
//          E1:                    -1.1E-005 
//          E2:                    -1.06E-005 
//          E3:                    -1.057E-005 
//        
//          e:                     -1.057300e-005 
//          e0:                    -1e-005 
//          e1:                    -1.1e-005 
//          e2:                    -1.06e-005 
//          e3:                    -1.057e-005 
//        
//          F:                     0.00 
//          F0:                    0 
//          F1:                    0.0 
//          F2:                    0.00 
//          F3:                    0.000 
//        
//          G:                     -1.0573E-05 
//          G0:                    -1.0573E-05 
//          G1:                    -1E-05 
//          G2:                    -1.1E-05 
//          G3:                    -1.06E-05 
//        
//          N:                     0.00 
//          N0:                    0 
//          N1:                    0.0 
//          N2:                    0.00 
//          N3:                    0.000 
//        
//          P:                     0.00 % 
//          P0:                    0 % 
//          P1:                    0.0 % 
//          P2:                    0.00 % 
//          P3:                    -0.001 % 
//        
//          R:                     -1.0573E-05 
//          #,000.000:             000.000 
//          0.###E-000:            -1.057E-005 
//          000,000,000,000.00###: -000,000,000,000.00001

Version Information

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.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

Platforms

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.

Reference

Other Resources

Formatting Types

How to: Pad a Number with Leading Zeros

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