Standard Numeric Format Strings

Standard numeric format strings are used to format common numeric types. A standard numeric format string takes the form Axx, where:

  • A is a single alphabetic character called the format specifier. Any numeric format string that contains more than one alphabetic character, including white space, is interpreted as a custom numeric format string. For more information, see Custom Numeric Format Strings.

  • xx is an optional integer called the precision specifier. The precision specifier ranges from 0 to 99 and affects the number of digits in the result. Note that the precision specifier controls the number of digits in the string representation of a number. It does not round the number itself. To perform a rounding operation, use the Math.Ceiling, Math.Floor, or Math.Round method.

    When precision specifier controls the number of fractional digits in the result string, the result strings reflect numbers that are rounded away from zero (that is, using MidpointRounding.AwayFromZero).

    Note

    The precision specifier determines the number of digits in the result string. To pad a result string with leading or trailing spaces, use the composite formatting feature and define an alignment component in the format item.

Standard numeric format strings are supported by:

Tip

You can download the Formatting Utility, an application that enables you to apply format strings to either numeric or date and time values and displays the result string.

The following table describes the standard numeric format specifiers and displays sample output produced by each format specifier. See the Notes section for additional information about using standard numeric format strings, and the Example section for a comprehensive illustration of their use.

Format specifier Name Description Examples
"C" or "c" Currency Result: A currency value.

Supported by: All numeric types.

Precision specifier: Number of decimal digits.

Default precision specifier: Defined by NumberFormatInfo.CurrencyDecimalDigits.

More information: The Currency ("C") Format Specifier.
123.456 ("C", en-US) -> $123.46

123.456 ("C", fr-FR) -> 123,46 €

123.456 ("C", ja-JP) -> ¥123

-123.456 ("C3", en-US) -> ($123.456)

-123.456 ("C3", fr-FR) -> -123,456 €

-123.456 ("C3", ja-JP) -> -¥123.456
"D" or "d" Decimal Result: Integer digits with optional negative sign.

Supported by: Integral types only.

Precision specifier: Minimum number of digits.

Default precision specifier: Minimum number of digits required.

More information: The Decimal("D") Format Specifier.
1234 ("D") -> 1234

-1234 ("D6") -> -001234
"E" or "e" Exponential (scientific) Result: Exponential notation.

Supported by: All numeric types.

Precision specifier: Number of decimal digits.

Default precision specifier: 6.

More information: The Exponential ("E") Format Specifier.
1052.0329112756 ("E", en-US) -> 1.052033E+003

1052.0329112756 ("e", fr-FR) -> 1,052033e+003

-1052.0329112756 ("e2", en-US) -> -1.05e+003

-1052.0329112756 ("E2", fr_FR) -> -1,05E+003
"F" or "f" Fixed-point Result: Integral and decimal digits with optional negative sign.

Supported by: All numeric types.

Precision specifier: Number of decimal digits.

Default precision specifier: Defined by NumberFormatInfo.NumberDecimalDigits.

More information: The Fixed-Point ("F") Format Specifier.
1234.567 ("F", en-US) -> 1234.57

1234.567 ("F", de-DE) -> 1234,57

1234 ("F1", en-US) -> 1234.0

1234 ("F1", de-DE) -> 1234,0

-1234.56 ("F4", en-US) -> -1234.5600

-1234.56 ("F4", de-DE) -> -1234,5600
"G" or "g" General Result: The more compact of either fixed-point or scientific notation.

Supported by: All numeric types.

Precision specifier: Number of significant digits.

Default precision specifier: Depends on numeric type.

More information: The General ("G") Format Specifier.
-123.456 ("G", en-US) -> -123.456

-123.456 ("G", sv-SE) -> -123,456

123.4546 ("G4", en-US) -> 123.5

123.4546 ("G4", sv-SE) -> 123,5

-1.234567890e-25 ("G", en-US) -> -1.23456789E-25

-1.234567890e-25 ("G", sv-SE) -> -1,23456789E-25
"N" or "n" Number Result: Integral and decimal digits, group separators, and a decimal separator with optional negative sign.

Supported by: All numeric types.

Precision specifier: Desired number of decimal places.

Default precision specifier: Defined by NumberFormatInfo.NumberDecimalDigits.

More information: The Numeric ("N") Format Specifier.
1234.567 ("N", en-US) -> 1,234.57

1234.567 ("N", ru-RU) -> 1 234,57

1234 ("N1", en-US) -> 1,234.0

1234 ("N1", ru-RU) -> 1 234,0

-1234.56 ("N3", en-US) -> -1,234.560

-1234.56 ("N3", ru-RU) -> -1 234,560
"P" or "p" Percent Result: Number multiplied by 100 and displayed with a percent symbol.

Supported by: All numeric types.

Precision specifier: Desired number of decimal places.

Default precision specifier: Defined by NumberFormatInfo.PercentDecimalDigits.

More information: The Percent ("P") Format Specifier.
1 ("P", en-US) -> 100.00 %

1 ("P", fr-FR) -> 100,00 %

-0.39678 ("P1", en-US) -> -39.7 %

-0.39678 ("P1", fr-FR) -> -39,7 %
"R" or "r" Round-trip Result: A string that can round-trip to an identical number.

Supported by: Single, Double, and BigInteger.

Note: Recommended for the BigInteger type only. For Double types, use "G17"; for Single types, use "G9".
Precision specifier: Ignored.

More information: The Round-trip ("R") Format Specifier.
123456789.12345678 ("R") -> 123456789.12345678

-1234567890.12345678 ("R") -> -1234567890.1234567
"X" or "x" Hexadecimal Result: A hexadecimal string.

Supported by: Integral types only.

Precision specifier: Number of digits in the result string.

More information: The HexaDecimal ("X") Format Specifier.
255 ("X") -> FF

-1 ("x") -> ff

255 ("x4") -> 00ff

-1 ("X4") -> 00FF
Any other single character Unknown specifier Result: Throws a FormatException at run time.

Using Standard Numeric Format Strings

A standard numeric format string can be used to define the formatting of a numeric value in one of two ways:

  • It can be passed to an overload of the ToString method that has a format parameter. The following example formats a numeric value as a currency string in the current culture (in this case, the en-US culture).

    Decimal value = static_cast<Decimal>(123.456);
    Console::WriteLine(value.ToString("C2"));
    // Displays $123.46
    
    decimal value = 123.456m;
    Console.WriteLine(value.ToString("C2"));
    // Displays $123.46
    
    Dim value As Decimal = 123.456d
    Console.WriteLine(value.ToString("C2"))         
    ' Displays $123.46
    
  • It can be supplied as the formatString argument in a format item used with such methods as String.Format, Console.WriteLine, and StringBuilder.AppendFormat. For more information, see Composite Formatting. The following example uses a format item to insert a currency value in a string.

    Decimal value = static_cast<Decimal>(123.456);
    Console::WriteLine("Your account balance is {0:C2}.", value);
    // Displays "Your account balance is $123.46."
    
    decimal value = 123.456m;
    Console.WriteLine("Your account balance is {0:C2}.", value);
    // Displays "Your account balance is $123.46."
    
    Dim value As Decimal = 123.456d
    Console.WriteLine("Your account balance is {0:C2}.", value)
    ' Displays "Your account balance is $123.46."
    

    Optionally, you can supply an alignment argument to specify the width of the numeric field and whether its value is right- or left-aligned. The following example left-aligns a currency value in a 28-character field, and it right-aligns a currency value in a 14-character field.

    array<Decimal>^ amounts = { static_cast<Decimal>(16305.32), 
                                static_cast<Decimal>(18794.16) };
    Console::WriteLine("   Beginning Balance           Ending Balance");
    Console::WriteLine("   {0,-28:C2}{1,14:C2}", amounts[0], amounts[1]);
    // Displays:
    //        Beginning Balance           Ending Balance
    //        $16,305.32                      $18,794.16      
    
    decimal[] amounts = { 16305.32m, 18794.16m };
    Console.WriteLine("   Beginning Balance           Ending Balance");
    Console.WriteLine("   {0,-28:C2}{1,14:C2}", amounts[0], amounts[1]);
    // Displays:
    //        Beginning Balance           Ending Balance
    //        $16,305.32                      $18,794.16      
    
    Dim amounts() As Decimal = { 16305.32d, 18794.16d }
    Console.WriteLine("   Beginning Balance           Ending Balance")
    Console.WriteLine("   {0,-28:C2}{1,14:C2}", amounts(0), amounts(1))
    ' Displays:
    '        Beginning Balance           Ending Balance
    '        $16,305.32                      $18,794.16      
    

The following sections provide detailed information about each of the standard numeric format strings.

The Currency ("C") Format Specifier

The "C" (or currency) format specifier converts a number to a string that represents a currency amount. The precision specifier indicates the desired number of decimal places in the result string. If the precision specifier is omitted, the default precision is defined by the NumberFormatInfo.CurrencyDecimalDigits property.

If the value to be formatted has more than the specified or default number of decimal places, the fractional value is rounded in the result string. If the value to the right of the number of specified decimal places is 5 or greater, the last digit in the result string is rounded away from zero.

The result string is affected by the formatting information of the current NumberFormatInfo object. The following table lists the NumberFormatInfo properties that control the formatting of the returned string.

NumberFormatInfo property Description
CurrencyPositivePattern Defines the placement of the currency symbol for positive values.
CurrencyNegativePattern Defines the placement of the currency symbol for negative values, and specifies whether the negative sign is represented by parentheses or the NegativeSign property.
NegativeSign Defines the negative sign used if CurrencyNegativePattern indicates that parentheses are not used.
CurrencySymbol Defines the currency symbol.
CurrencyDecimalDigits Defines the default number of decimal digits in a currency value. This value can be overridden by using the precision specifier.
CurrencyDecimalSeparator Defines the string that separates integral and decimal digits.
CurrencyGroupSeparator Defines the string that separates groups of integral numbers.
CurrencyGroupSizes Defines the number of integer digits that appear in a group.

The following example formats a Double value with the currency format specifier.

double value = 12345.6789;
Console::WriteLine(value.ToString("C", CultureInfo::CurrentCulture));

Console::WriteLine(value.ToString("C3", CultureInfo::CurrentCulture));

Console::WriteLine(value.ToString("C3", 
                  CultureInfo::CreateSpecificCulture("da-DK")));
// The example displays the following output on a system whose
// current culture is English (United States):
//       $12,345.68
//       $12,345.679
//       kr 12.345,679
double value = 12345.6789;
Console.WriteLine(value.ToString("C", CultureInfo.CurrentCulture));

Console.WriteLine(value.ToString("C3", CultureInfo.CurrentCulture));

Console.WriteLine(value.ToString("C3", 
                  CultureInfo.CreateSpecificCulture("da-DK")));
// The example displays the following output on a system whose
// current culture is English (United States):
//       $12,345.68
//       $12,345.679
//       kr 12.345,679
Dim value As Double = 12345.6789
Console.WriteLine(value.ToString("C", CultureInfo.CurrentCulture))

Console.WriteLine(value.ToString("C3", CultureInfo.CurrentCulture))

Console.WriteLine(value.ToString("C3", _
                  CultureInfo.CreateSpecificCulture("da-DK")))
' The example displays the following output on a system whose
' current culture is English (United States):
'       $12,345.68
'       $12,345.679
'       kr 12.345,679

Back to table

The Decimal ("D") Format Specifier

The "D" (or decimal) format specifier converts a number to a string of decimal digits (0-9), prefixed by a minus sign if the number is negative. This format is supported only for integral types.

The precision specifier indicates the minimum number of digits desired in the resulting string. If required, the number is padded with zeros to its left to produce the number of digits given by the precision specifier. If no precision specifier is specified, the default is the minimum value required to represent the integer without leading zeros.

The result string is affected by the formatting information of the current NumberFormatInfo object. As the following table shows, a single property affects the formatting of the result string.

NumberFormatInfo property Description
NegativeSign Defines the string that indicates that a number is negative.

The following example formats an Int32 value with the decimal format specifier.

int value; 

value = 12345;
Console::WriteLine(value.ToString("D"));
// Displays 12345
Console::WriteLine(value.ToString("D8"));
// Displays 00012345

value = -12345;
Console::WriteLine(value.ToString("D"));
// Displays -12345
Console::WriteLine(value.ToString("D8"));
// Displays -00012345
int value; 

value = 12345;
Console.WriteLine(value.ToString("D"));
// Displays 12345
Console.WriteLine(value.ToString("D8"));
// Displays 00012345

value = -12345;
Console.WriteLine(value.ToString("D"));
// Displays -12345
Console.WriteLine(value.ToString("D8"));
// Displays -00012345
Dim value As Integer 

value = 12345
Console.WriteLine(value.ToString("D"))
' Displays 12345   
Console.WriteLine(value.ToString("D8"))
' Displays 00012345

value = -12345
Console.WriteLine(value.ToString("D"))
' Displays -12345
Console.WriteLine(value.ToString("D8"))
' Displays -00012345

Back to table

The Exponential ("E") Format Specifier

The exponential ("E") format specifier converts a number to a string of the form "-d.ddd…E+ddd" or "-d.ddd…e+ddd", where each "d" indicates a digit (0-9). The string starts with a minus sign if the number is negative. Exactly one digit always precedes the decimal point.

The precision specifier indicates the desired number of digits after the decimal point. If the precision specifier is omitted, a default of six digits after the decimal point is used.

The case of the format specifier indicates whether to prefix the exponent with an "E" or an "e". The exponent always consists of a plus or minus sign and a minimum of three digits. The exponent is padded with zeros to meet this minimum, if required.

The result string is affected by the formatting information of the current NumberFormatInfo object. The following table lists the NumberFormatInfo properties that control the formatting of the returned string.

NumberFormatInfo property Description
NegativeSign Defines the string that indicates that a number is negative for both the coefficient and exponent.
NumberDecimalSeparator Defines the string that separates the integral digit from decimal digits in the coefficient.
PositiveSign Defines the string that indicates that an exponent is positive.

The following example formats a Double value with the exponential format specifier.

double value = 12345.6789;
Console::WriteLine(value.ToString("E", CultureInfo::InvariantCulture));
// Displays 1.234568E+004

Console::WriteLine(value.ToString("E10", CultureInfo::InvariantCulture));
// Displays 1.2345678900E+004

Console::WriteLine(value.ToString("e4", CultureInfo::InvariantCulture));
// Displays 1.2346e+004

Console::WriteLine(value.ToString("E", 
                  CultureInfo::CreateSpecificCulture("fr-FR")));
// Displays 1,234568E+004
double value = 12345.6789;
Console.WriteLine(value.ToString("E", CultureInfo.InvariantCulture));
// Displays 1.234568E+004

Console.WriteLine(value.ToString("E10", CultureInfo.InvariantCulture));
// Displays 1.2345678900E+004

Console.WriteLine(value.ToString("e4", CultureInfo.InvariantCulture));
// Displays 1.2346e+004

Console.WriteLine(value.ToString("E", 
                  CultureInfo.CreateSpecificCulture("fr-FR")));
// Displays 1,234568E+004
Dim value As Double = 12345.6789
Console.WriteLine(value.ToString("E", CultureInfo.InvariantCulture))
' Displays 1.234568E+004

Console.WriteLine(value.ToString("E10", CultureInfo.InvariantCulture))
' Displays 1.2345678900E+004

Console.WriteLine(value.ToString("e4", CultureInfo.InvariantCulture))
' Displays 1.2346e+004

Console.WriteLine(value.ToString("E", _
                  CultureInfo.CreateSpecificCulture("fr-FR")))
' Displays 1,234568E+004

Back to table

The Fixed-Point ("F") Format Specifier

The fixed-point ("F") format specifier converts a number to a string of the form "-ddd.ddd…" where each "d" indicates a digit (0-9). The string starts with a minus sign if the number is negative.

The precision specifier indicates the desired number of decimal places. If the precision specifier is omitted, the current NumberFormatInfo.NumberDecimalDigits property supplies the numeric precision.

The result string is affected by the formatting information of the current NumberFormatInfo object. The following table lists the properties of the NumberFormatInfo object that control the formatting of the result string.

NumberFormatInfo property Description
NegativeSign Defines the string that indicates that a number is negative.
NumberDecimalSeparator Defines the string that separates integral digits from decimal digits.
NumberDecimalDigits Defines the default number of decimal digits. This value can be overridden by using the precision specifier.

The following example formats a Double and an Int32 value with the fixed-point format specifier.

int integerNumber;
integerNumber = 17843;
Console::WriteLine(integerNumber.ToString("F", 
                  CultureInfo::InvariantCulture));
// Displays 17843.00

integerNumber = -29541;
Console::WriteLine(integerNumber.ToString("F3", 
                  CultureInfo::InvariantCulture));
// Displays -29541.000

double doubleNumber;
doubleNumber = 18934.1879;
Console::WriteLine(doubleNumber.ToString("F", CultureInfo::InvariantCulture));
// Displays 18934.19

Console::WriteLine(doubleNumber.ToString("F0", CultureInfo::InvariantCulture));
// Displays 18934

doubleNumber = -1898300.1987;
Console::WriteLine(doubleNumber.ToString("F1", CultureInfo::InvariantCulture));  
// Displays -1898300.2

Console::WriteLine(doubleNumber.ToString("F3", 
                  CultureInfo::CreateSpecificCulture("es-ES")));
// Displays -1898300,199                        
int integerNumber;
integerNumber = 17843;
Console.WriteLine(integerNumber.ToString("F", 
                  CultureInfo.InvariantCulture));
// Displays 17843.00

integerNumber = -29541;
Console.WriteLine(integerNumber.ToString("F3", 
                  CultureInfo.InvariantCulture));
// Displays -29541.000

double doubleNumber;
doubleNumber = 18934.1879;
Console.WriteLine(doubleNumber.ToString("F", CultureInfo.InvariantCulture));
// Displays 18934.19

Console.WriteLine(doubleNumber.ToString("F0", CultureInfo.InvariantCulture));
// Displays 18934

doubleNumber = -1898300.1987;
Console.WriteLine(doubleNumber.ToString("F1", CultureInfo.InvariantCulture));  
// Displays -1898300.2

Console.WriteLine(doubleNumber.ToString("F3", 
                  CultureInfo.CreateSpecificCulture("es-ES")));
// Displays -1898300,199                        
Dim integerNumber As Integer
integerNumber = 17843
Console.WriteLine(integerNumber.ToString("F", CultureInfo.InvariantCulture))
' Displays 17843.00

integerNumber = -29541
Console.WriteLine(integerNumber.ToString("F3", CultureInfo.InvariantCulture))
' Displays -29541.000

Dim doubleNumber As Double
doubleNumber = 18934.1879
Console.WriteLine(doubleNumber.ToString("F", CultureInfo.InvariantCulture))
' Displays 18934.19

Console.WriteLine(doubleNumber.ToString("F0", CultureInfo.InvariantCulture))
' Displays 18934

doubleNumber = -1898300.1987
Console.WriteLine(doubleNumber.ToString("F1", CultureInfo.InvariantCulture))  
' Displays -1898300.2

Console.WriteLine(doubleNumber.ToString("F3", _ 
                  CultureInfo.CreateSpecificCulture("es-ES")))
' Displays -1898300,199                        

Back to table

The General ("G") Format Specifier

The general ("G") format specifier converts a number to the more compact of either fixed-point or scientific notation, depending on the type of the number and whether a precision specifier is present. The precision specifier defines the maximum number of significant digits that can appear in the result string. If the precision specifier is omitted or zero, the type of the number determines the default precision, as indicated in the following table.

Numeric type Default precision
Byte or SByte 3 digits
Int16 or UInt16 5 digits
Int32 or UInt32 10 digits
Int64 19 digits
UInt64 20 digits
BigInteger Unlimited (same as "R")
Single 7 digits
Double 15 digits
Decimal 29 digits

Fixed-point notation is used if the exponent that would result from expressing the number in scientific notation is greater than -5 and less than the precision specifier; otherwise, scientific notation is used. The result contains a decimal point if required, and trailing zeros after the decimal point are omitted. If the precision specifier is present and the number of significant digits in the result exceeds the specified precision, the excess trailing digits are removed by rounding.

However, if the number is a Decimal and the precision specifier is omitted, fixed-point notation is always used and trailing zeros are preserved.

If scientific notation is used, the exponent in the result is prefixed with "E" if the format specifier is "G", or "e" if the format specifier is "g". The exponent contains a minimum of two digits. This differs from the format for scientific notation that is produced by the exponential format specifier, which includes a minimum of three digits in the exponent.

Note that, when used with a Double value, the "G17" format specifier ensures that the original Double value successfully round-trips. This is because Double is an IEEE 754-2008-compliant double-precision (binary64) floating point number that gives up to 17 significant digits of precision. We recommend its use instead of the "R" format specifier, since in some cases "R" fails to successfully round-trip double-precision floating point values. The following example illustrates one such case.

using System;

public class Example
{
   public static void Main()
   {
      double original = 0.84551240822557006;
      var rSpecifier = original.ToString("R");
      var g17Specifier = original.ToString("G17");
      
      var rValue = Double.Parse(rSpecifier);
      var g17Value = Double.Parse(g17Specifier);
      
      Console.WriteLine($"{original:G17} = {rSpecifier} (R): {original.Equals(rValue)}");
      Console.WriteLine($"{original:G17} = {g17Specifier} (G17): {original.Equals(g17Value)}");
   }
}
// The example displays the following output:
//     0.84551240822557006 = 0.84551240822557: False
//     0.84551240822557006 = 0.84551240822557006: True
Module Example
   Public Sub Main()
      Dim original As Double = 0.84551240822557006
      Dim rSpecifier = original.ToString("R")
      Dim g17Specifier = original.ToString("G17")
      
      Dim rValue = Double.Parse(rSpecifier)
      Dim g17Value = Double.Parse(g17Specifier)
      
      Console.WriteLine($"{original:G17} = {rSpecifier} (R): {original.Equals(rValue)}")
      Console.WriteLine($"{original:G17} = {g17Specifier} (G17): {original.Equals(g17Value)}")
   End Sub
End Module
' The example displays the following output:
'     0.84551240822557006 = 0.84551240822557 (R): False
'     0.84551240822557006 = 0.84551240822557006 (G17): True
  

When used with a Single value, the "G9" format specifier ensures that the original Single value successfully round-trips. This is because Single is an IEEE 754-2008-compliant single-precision (binary32) floating point number that gives up to nine significant digits of precision. We recommend its use instead of the "R" format specifier, since in some cases "R" fails to successfully round-trip single-precision floating point values.

The result string is affected by the formatting information of the current NumberFormatInfo object. The following table lists the NumberFormatInfo properties that control the formatting of the result string.

NumberFormatInfo property Description
NegativeSign Defines the string that indicates that a number is negative.
NumberDecimalSeparator Defines the string that separates integral digits from decimal digits.
PositiveSign Defines the string that indicates that an exponent is positive.

The following example formats assorted floating-point values with the general format specifier.

double number;

number = 12345.6789;      
Console::WriteLine(number.ToString("G", CultureInfo::InvariantCulture));
// Displays  12345.6789
Console::WriteLine(number.ToString("G", 
                  CultureInfo::CreateSpecificCulture("fr-FR")));
// Displays 12345,6789
                        
Console::WriteLine(number.ToString("G7", CultureInfo::InvariantCulture));
// Displays 12345.68 

number = .0000023;
Console::WriteLine(number.ToString("G", CultureInfo::InvariantCulture));
// Displays 2.3E-06       
Console::WriteLine(number.ToString("G", 
                  CultureInfo::CreateSpecificCulture("fr-FR")));
// Displays 2,3E-06

number = .0023;
Console::WriteLine(number.ToString("G", CultureInfo::InvariantCulture));
// Displays 0.0023

number = 1234;
Console::WriteLine(number.ToString("G2", CultureInfo::InvariantCulture));
// Displays 1.2E+03

number = Math::PI;
Console::WriteLine(number.ToString("G5", CultureInfo::InvariantCulture));
// Displays 3.1416    
double number;

number = 12345.6789;      
Console.WriteLine(number.ToString("G", CultureInfo.InvariantCulture));
// Displays  12345.6789
Console.WriteLine(number.ToString("G", 
                  CultureInfo.CreateSpecificCulture("fr-FR")));
// Displays 12345,6789
                        
Console.WriteLine(number.ToString("G7", CultureInfo.InvariantCulture));
// Displays 12345.68 

number = .0000023;
Console.WriteLine(number.ToString("G", CultureInfo.InvariantCulture));
// Displays 2.3E-06       
Console.WriteLine(number.ToString("G", 
                  CultureInfo.CreateSpecificCulture("fr-FR")));
// Displays 2,3E-06

number = .0023;
Console.WriteLine(number.ToString("G", CultureInfo.InvariantCulture));
// Displays 0.0023

number = 1234;
Console.WriteLine(number.ToString("G2", CultureInfo.InvariantCulture));
// Displays 1.2E+03

number = Math.PI;
Console.WriteLine(number.ToString("G5", CultureInfo.InvariantCulture));
// Displays 3.1416    
Dim number As Double

number = 12345.6789      
Console.WriteLine(number.ToString("G", CultureInfo.InvariantCulture))
' Displays  12345.6789
Console.WriteLine(number.ToString("G", _
                  CultureInfo.CreateSpecificCulture("fr-FR")))
' Displays 12345,6789
                        
Console.WriteLine(number.ToString("G7", CultureInfo.InvariantCulture))
' Displays 12345.68 

number = .0000023
Console.WriteLine(number.ToString("G", CultureInfo.InvariantCulture))
' Displays 2.3E-06       
Console.WriteLine(number.ToString("G", _
                  CultureInfo.CreateSpecificCulture("fr-FR")))
' Displays 2,3E-06

number = .0023
Console.WriteLine(number.ToString("G", CultureInfo.InvariantCulture))
' Displays 0.0023

number = 1234
Console.WriteLine(number.ToString("G2", CultureInfo.InvariantCulture))
' Displays 1.2E+03

number = Math.Pi
Console.WriteLine(number.ToString("G5", CultureInfo.InvariantCulture))
' Displays 3.1416    

Back to table

The Numeric ("N") Format Specifier

The numeric ("N") format specifier converts a number to a string of the form "-d,ddd,ddd.ddd…", where "-" indicates a negative number symbol if required, "d" indicates a digit (0-9), "," indicates a group separator, and "." indicates a decimal point symbol. The precision specifier indicates the desired number of digits after the decimal point. If the precision specifier is omitted, the number of decimal places is defined by the current NumberFormatInfo.NumberDecimalDigits property.

The result string is affected by the formatting information of the current NumberFormatInfo object. The following table lists the NumberFormatInfo properties that control the formatting of the result string.

NumberFormatInfo property Description
NegativeSign Defines the string that indicates that a number is negative.
NumberNegativePattern Defines the format of negative values, and specifies whether the negative sign is represented by parentheses or the NegativeSign property.
NumberGroupSizes Defines the number of integral digits that appear between group separators.
NumberGroupSeparator Defines the string that separates groups of integral numbers.
NumberDecimalSeparator Defines the string that separates integral and decimal digits.
NumberDecimalDigits Defines the default number of decimal digits. This value can be overridden by using a precision specifier.

The following example formats assorted floating-point values with the number format specifier.

double dblValue = -12445.6789;
Console::WriteLine(dblValue.ToString("N", CultureInfo::InvariantCulture));
// Displays -12,445.68
Console::WriteLine(dblValue.ToString("N1", 
                  CultureInfo::CreateSpecificCulture("sv-SE")));
// Displays -12 445,7

int intValue = 123456789;
Console::WriteLine(intValue.ToString("N1", CultureInfo::InvariantCulture));
// Displays 123,456,789.0 
double dblValue = -12445.6789;
Console.WriteLine(dblValue.ToString("N", CultureInfo.InvariantCulture));
// Displays -12,445.68
Console.WriteLine(dblValue.ToString("N1", 
                  CultureInfo.CreateSpecificCulture("sv-SE")));
// Displays -12 445,7

int intValue = 123456789;
Console.WriteLine(intValue.ToString("N1", CultureInfo.InvariantCulture));
// Displays 123,456,789.0 
Dim dblValue As Double = -12445.6789
Console.WriteLine(dblValue.ToString("N", CultureInfo.InvariantCulture))
' Displays -12,445.68
Console.WriteLine(dblValue.ToString("N1", _
                  CultureInfo.CreateSpecificCulture("sv-SE")))
' Displays -12 445,7

Dim intValue As Integer = 123456789
Console.WriteLine(intValue.ToString("N1", CultureInfo.InvariantCulture))
' Displays 123,456,789.0 

Back to table

The Percent ("P") Format Specifier

The percent ("P") format specifier multiplies a number by 100 and converts it to a string that represents a percentage. The precision specifier indicates the desired number of decimal places. If the precision specifier is omitted, the default numeric precision supplied by the current PercentDecimalDigits property is used.

The following table lists the NumberFormatInfo properties that control the formatting of the returned string.

NumberFormatInfo property Description
PercentPositivePattern Defines the placement of the percent symbol for positive values.
PercentNegativePattern Defines the placement of the percent symbol and the negative symbol for negative values.
NegativeSign Defines the string that indicates that a number is negative.
PercentSymbol Defines the percent symbol.
PercentDecimalDigits Defines the default number of decimal digits in a percentage value. This value can be overridden by using the precision specifier.
PercentDecimalSeparator Defines the string that separates integral and decimal digits.
PercentGroupSeparator Defines the string that separates groups of integral numbers.
PercentGroupSizes Defines the number of integer digits that appear in a group.

The following example formats floating-point values with the percent format specifier.

double number = .2468013;
Console::WriteLine(number.ToString("P", CultureInfo::InvariantCulture));
// Displays 24.68 %
Console::WriteLine(number.ToString("P", 
                  CultureInfo::CreateSpecificCulture("hr-HR")));
// Displays 24,68%     
Console::WriteLine(number.ToString("P1", CultureInfo::InvariantCulture));
// Displays 24.7 %
double number = .2468013;
Console.WriteLine(number.ToString("P", CultureInfo.InvariantCulture));
// Displays 24.68 %
Console.WriteLine(number.ToString("P", 
                  CultureInfo.CreateSpecificCulture("hr-HR")));
// Displays 24,68%     
Console.WriteLine(number.ToString("P1", CultureInfo.InvariantCulture));
// Displays 24.7 %
Dim number As Double = .2468013
Console.WriteLine(number.ToString("P", CultureInfo.InvariantCulture))
' Displays 24.68 %
Console.WriteLine(number.ToString("P", _
                  CultureInfo.CreateSpecificCulture("hr-HR")))
' Displays 24,68%     
Console.WriteLine(number.ToString("P1", CultureInfo.InvariantCulture))
' Displays 24.7 %

Back to table

The Round-trip ("R") Format Specifier

The round-trip ("R") format specifier attempts to ensure that a numeric value that is converted to a string is parsed back into the same numeric value. This format is supported only for the Single, Double, and BigInteger types.

For Double and Single values, the "R" format specifier in some cases fails to successfully round-trip the original value and also offers relatively poor performance. Instead, we recommend that you use the "G17" format specifier for Double values and the "G9" format specifier to successfully round-trip Single values.

When a BigInteger value is formatted using this specifier, its string representation contains all the significant digits in the BigInteger value.

Although you can include a precision specifier, it is ignored. Round trips are given precedence over precision when using this specifier.
The result string is affected by the formatting information of the current NumberFormatInfo object. The following table lists the NumberFormatInfo properties that control the formatting of the result string.

NumberFormatInfo property Description
NegativeSign Defines the string that indicates that a number is negative.
NumberDecimalSeparator Defines the string that separates integral digits from decimal digits.
PositiveSign Defines the string that indicates that an exponent is positive.

The following example formats a BigInteger value with the round-trip format specifier.

#using <System.Numerics.dll>

using namespace System;
using namespace System::Numerics;

void main()
{ 
   BigInteger value = BigInteger::Pow(Int64::MaxValue, 2);
   Console::WriteLine(value.ToString("R"));
}
// The example displays the following output:
//      85070591730234615847396907784232501249  


using System;
using System.Numerics;

public class Example
{
   public static void Main()
   { 
      var value = BigInteger.Pow(Int64.MaxValue, 2);
      Console.WriteLine(value.ToString("R"));
   }
}                                                                                        // The example displays the following output:
//      85070591730234615847396907784232501249  


Imports System.Numerics

Module Example
   Public Sub Main()
      Dim value = BigInteger.Pow(Int64.MaxValue, 2)
      Console.WriteLine(value.ToString("R"))
   End Sub
End Module
' The example displays the following output:
'      85070591730234615847396907784232501249  

Important

In some cases, Double values formatted with the "R" standard numeric format string do not successfully round-trip if compiled using the /platform:x64 or /platform:anycpu switches and run on 64-bit systems. See the following paragraph for more information.

To work around the problem of Double values formatted with the "R" standard numeric format string not successfully round-tripping if compiled using the /platform:x64 or /platform:anycpu switches and run on 64-bit systems., you can format Double values by using the "G17" standard numeric format string. The following example uses the "R" format string with a Double value that does not round-trip successfully, and also uses the "G17" format string to successfully round-trip the original value.

using System;
using System.Globalization;

public class Example
{
   static void Main(string[] args)
   {
      Console.WriteLine("Attempting to round-trip a Double with 'R':");
      double initialValue = 0.6822871999174;
      string valueString = initialValue.ToString("R",
                                                 CultureInfo.InvariantCulture);
      double roundTripped = double.Parse(valueString,
                                         CultureInfo.InvariantCulture);
      Console.WriteLine("{0:R} = {1:R}: {2}\n",
                        initialValue, roundTripped, initialValue.Equals(roundTripped));

      Console.WriteLine("Attempting to round-trip a Double with 'G17':");
      string valueString17 = initialValue.ToString("G17",
                                                   CultureInfo.InvariantCulture);
      double roundTripped17 = double.Parse(valueString17,
                                           CultureInfo.InvariantCulture);
      Console.WriteLine("{0:R} = {1:R}: {2}\n",
                        initialValue, roundTripped17, initialValue.Equals(roundTripped17));
   }
}
// If compiled to an application that targets anycpu or x64 and run on an x64 system,
// the example displays the following output:
//       Attempting to round-trip a Double with 'R':
//       0.6822871999174 = 0.68228719991740006: False
//
//       Attempting to round-trip a Double with 'G17':
//       0.6822871999174 = 0.6822871999174: True
Imports System.Globalization

Module Example
   Public Sub Main()
      Console.WriteLine("Attempting to round-trip a Double with 'R':")
      Dim initialValue As Double = 0.6822871999174
      Dim valueString As String = initialValue.ToString("R",
                                               CultureInfo.InvariantCulture)
      Dim roundTripped As Double = Double.Parse(valueString,
                                                CultureInfo.InvariantCulture)
      Console.WriteLine("{0:R} = {1:R}: {2}",
                        initialValue, roundTripped, initialValue.Equals(roundTripped))
      Console.WriteLine()
      
      Console.WriteLine("Attempting to round-trip a Double with 'G17':")
      Dim valueString17 As String = initialValue.ToString("G17",
                                                 CultureInfo.InvariantCulture)
      Dim roundTripped17 As Double = double.Parse(valueString17,
                                            CultureInfo.InvariantCulture)
      Console.WriteLine("{0:R} = {1:R}: {2}",
                        initialValue, roundTripped17, initialValue.Equals(roundTripped17))
   End Sub
End Module
' If compiled to an application that targets anycpu or x64 and run on an x64 system,
' the example displays the following output:
'       Attempting to round-trip a Double with 'R':
'       0.6822871999174 = 0.68228719991740006: False
'
'       Attempting to round-trip a Double with 'G17':
'       0.6822871999174 = 0.6822871999174: True

Back to table

The Hexadecimal ("X") Format Specifier

The hexadecimal ("X") format specifier converts a number to a string of hexadecimal digits. The case of the format specifier indicates whether to use uppercase or lowercase characters for hexadecimal digits that are greater than 9. For example, use "X" to produce "ABCDEF", and "x" to produce "abcdef". This format is supported only for integral types.

The precision specifier indicates the minimum number of digits desired in the resulting string. If required, the number is padded with zeros to its left to produce the number of digits given by the precision specifier.

The result string is not affected by the formatting information of the current NumberFormatInfo object.

The following example formats Int32 values with the hexadecimal format specifier.

int value; 

value = 0x2045e;
Console::WriteLine(value.ToString("x"));
// Displays 2045e
Console::WriteLine(value.ToString("X"));
// Displays 2045E
Console::WriteLine(value.ToString("X8"));
// Displays 0002045E

value = 123456789;
Console::WriteLine(value.ToString("X"));
// Displays 75BCD15
Console::WriteLine(value.ToString("X2"));
// Displays 75BCD15
int value; 

value = 0x2045e;
Console.WriteLine(value.ToString("x"));
// Displays 2045e
Console.WriteLine(value.ToString("X"));
// Displays 2045E
Console.WriteLine(value.ToString("X8"));
// Displays 0002045E

value = 123456789;
Console.WriteLine(value.ToString("X"));
// Displays 75BCD15
Console.WriteLine(value.ToString("X2"));
// Displays 75BCD15
Dim value As Integer 

value = &h2045e
Console.WriteLine(value.ToString("x"))
' Displays 2045e
Console.WriteLine(value.ToString("X"))
' Displays 2045E
Console.WriteLine(value.ToString("X8"))
' Displays 0002045E

value = 123456789
Console.WriteLine(value.ToString("X"))
' Displays 75BCD15
Console.WriteLine(value.ToString("X2"))
' Displays 75BCD15

Back to table

Notes

Control Panel Settings

The settings in the Regional and Language Options item in Control Panel influence the result string produced by a formatting operation. Those settings are used to initialize the NumberFormatInfo object associated with the current thread culture, which provides values used to govern formatting. Computers that use different settings generate different result strings.

In addition, if the CultureInfo.CultureInfo(String) constructor is used to instantiate a new CultureInfo object that represents the same culture as the current system culture, any customizations established by the Regional and Language Options item in Control Panel will be applied to the new CultureInfo object. You can use the CultureInfo.CultureInfo(String, Boolean) constructor to create a CultureInfo object that does not reflect a system's customizations.

NumberFormatInfo Properties

Formatting is influenced by the properties of the current NumberFormatInfo object, which is provided implicitly by the current thread culture or explicitly by the IFormatProvider parameter of the method that invokes formatting. Specify a NumberFormatInfo or CultureInfo object for that parameter.

Note

For information about customizing the patterns or strings used in formatting numeric values, see the NumberFormatInfo class topic.

Integral and Floating-Point Numeric Types

Some descriptions of standard numeric format specifiers refer to integral or floating-point numeric types. The integral numeric types are Byte, SByte, Int16, Int32, Int64, UInt16, UInt32, UInt64, and BigInteger. The floating-point numeric types are Decimal, Single, and Double.

Floating-Point Infinities and NaN

Regardless of the format string, if the value of a Single or Double floating-point type is positive infinity, negative infinity, or not a number (NaN), the formatted string is the value of the respective PositiveInfinitySymbol, NegativeInfinitySymbol, or NaNSymbol property that is specified by the currently applicable NumberFormatInfo object.

Example

The following example formats an integral and a floating-point numeric value using the en-US culture and all the standard numeric format specifiers. This example uses two particular numeric types (Double and Int32), but would yield similar results for any of the other numeric base types (Byte, SByte, Int16, Int32, Int64, UInt16, UInt32, UInt64, BigInteger, Decimal, and Single).

using System;
using System.Globalization;
using System.Threading;

public class NumericFormats
{
   public static void Main()
   {
      // Display string representations of numbers for en-us culture
      CultureInfo ci = new CultureInfo("en-us");
      
      // Output floating point values
      double floating = 10761.937554;
      Console.WriteLine("C: {0}", 
              floating.ToString("C", ci));           // Displays "C: $10,761.94"
      Console.WriteLine("E: {0}", 
              floating.ToString("E03", ci));         // Displays "E: 1.076E+004"
      Console.WriteLine("F: {0}", 
              floating.ToString("F04", ci));         // Displays "F: 10761.9376"         
      Console.WriteLine("G: {0}",  
              floating.ToString("G", ci));           // Displays "G: 10761.937554"
      Console.WriteLine("N: {0}", 
              floating.ToString("N03", ci));         // Displays "N: 10,761.938"
      Console.WriteLine("P: {0}", 
              (floating/10000).ToString("P02", ci)); // Displays "P: 107.62 %"
      Console.WriteLine("R: {0}", 
              floating.ToString("R", ci));           // Displays "R: 10761.937554"            
      Console.WriteLine();
      
      // Output integral values
      int integral = 8395;
      Console.WriteLine("C: {0}", 
              integral.ToString("C", ci));           // Displays "C: $8,395.00"
      Console.WriteLine("D: {0}", 
              integral.ToString("D6", ci));          // Displays "D: 008395" 
      Console.WriteLine("E: {0}", 
              integral.ToString("E03", ci));         // Displays "E: 8.395E+003"
      Console.WriteLine("F: {0}", 
              integral.ToString("F01", ci));         // Displays "F: 8395.0"    
      Console.WriteLine("G: {0}",  
              integral.ToString("G", ci));           // Displays "G: 8395"
      Console.WriteLine("N: {0}", 
              integral.ToString("N01", ci));         // Displays "N: 8,395.0"
      Console.WriteLine("P: {0}", 
              (integral/10000.0).ToString("P02", ci)); // Displays "P: 83.95 %"
      Console.WriteLine("X: 0x{0}", 
              integral.ToString("X", ci));           // Displays "X: 0x20CB"
      Console.WriteLine();
   }
}
Option Strict On

Imports System.Globalization
Imports System.Threading

Module NumericFormats
   Public Sub Main()
      ' Display string representations of numbers for en-us culture
      Dim ci As New CultureInfo("en-us")
      
      ' Output floating point values
      Dim floating As Double = 10761.937554
      Console.WriteLine("C: {0}", _
              floating.ToString("C", ci))           ' Displays "C: $10,761.94"
      Console.WriteLine("E: {0}", _
              floating.ToString("E03", ci))         ' Displays "E: 1.076E+004"
      Console.WriteLine("F: {0}", _
              floating.ToString("F04", ci))         ' Displays "F: 10761.9376"         
      Console.WriteLine("G: {0}", _ 
              floating.ToString("G", ci))           ' Displays "G: 10761.937554"
      Console.WriteLine("N: {0}", _
              floating.ToString("N03", ci))         ' Displays "N: 10,761.938"
      Console.WriteLine("P: {0}", _
              (floating/10000).ToString("P02", ci)) ' Displays "P: 107.62 %"
      Console.WriteLine("R: {0}", _
              floating.ToString("R", ci))           ' Displays "R: 10761.937554"            
      Console.WriteLine()
      
      ' Output integral values
      Dim integral As Integer = 8395
      Console.WriteLine("C: {0}", _
              integral.ToString("C", ci))           ' Displays "C: $8,395.00"
      Console.WriteLine("D: {0}", _
              integral.ToString("D6"))              ' Displays "D: 008395" 
      Console.WriteLine("E: {0}", _
              integral.ToString("E03", ci))         ' Displays "E: 8.395E+003"
      Console.WriteLine("F: {0}", _
              integral.ToString("F01", ci))         ' Displays "F: 8395.0"    
      Console.WriteLine("G: {0}", _ 
              integral.ToString("G", ci))           ' Displays "G: 8395"
      Console.WriteLine("N: {0}", _
              integral.ToString("N01", ci))         ' Displays "N: 8,395.0"
      Console.WriteLine("P: {0}", _
              (integral/10000).ToString("P02", ci)) ' Displays "P: 83.95 %"
      Console.WriteLine("X: 0x{0}", _
              integral.ToString("X", ci))           ' Displays "X: 0x20CB"
      Console.WriteLine()
   End Sub
End Module

See Also

NumberFormatInfo
Custom Numeric Format Strings
Formatting Types
How to: Pad a Number with Leading Zeros
Sample: .NET Framework 4 Formatting Utility
Composite Formatting