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Double.Parse Method (String, NumberStyles)

Updated: May 2009

Converts the string representation of a number in a specified style to its double-precision floating-point number equivalent.

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

public static double Parse(
	string s,
	NumberStyles style
)

Parameters

s
Type: System.String

A string containing a number to convert.

style
Type: System.Globalization.NumberStyles

A bitwise combination of NumberStyles values that indicates the style elements that can be present in s. A typical value to specify is a combination of NumberStyles.Float and NumberStyles.AllowThousands.

Return Value

Type: System.Double
A double-precision floating-point number equivalent to the numeric value or symbol specified in s. Because of differences in precision, the return value may not be exactly equal to s, and for values of s that are less than Epsilon, the return value may also differ depending on processor architecture. For more information, see the Remarks section of Double.

ExceptionCondition
ArgumentNullException

s is null.

FormatException

s is not a number in a valid format.

OverflowException

s represents a number less than MinValue or greater than MaxValue.

ArgumentException

style is not a NumberStyles value.

-or-

style is the AllowHexSpecifier value.

The style parameter defines the style elements (such as white space, thousands separators, and currency symbols) that are allowed in the s parameter for the parse operation to succeed. It must be a combination of bit flags from the NumberStyles enumeration. The following NumberStyles members are not supported:

The s parameter can contain the current culture's NumberFormatInfo.PositiveInfinitySymbol, NumberFormatInfo.NegativeInfinitySymbol, or NumberFormatInfo.NaNSymbol. Depending on the value of style, it can also take the form:

[ws][$][sign][integral-digits[,]]integral-digits[.[fractional-digits]][e[sign]exponential-digits][ws]

Elements in square brackets ([ and ]) are optional. The following table describes each element.

Element

Description

ws

A series of white space characters. White space can appear at the beginning of s if style includes the NumberStyles.AllowLeadingWhite flag, and it can appear at the end of s if style includes the NumberStyles.AllowTrailingWhite flag.

$

A culture-specific currency symbol. Its position in the string is defined by the NumberFormatInfo.CurrencyNegativePattern and NumberFormatInfo.CurrencyPositivePattern properties of the current culture. The current culture's currency symbol can appear in s if style includes the NumberStyles.AllowCurrencySymbol flag.

sign

A negative sign or positive sign symbol. The sign can appear at the beginning of s if style includes the NumberStyles.AllowLeadingSign flag, and it can appear at the end of s if style includes the NumberStyles.AllowTrailingSign flag. Parentheses can be used in s to indicate a negative value if style includes the NumberStyles.AllowParentheses flag.

integral-digits

A series of digits ranging from 0 to 9 that specify the integral part of the number. Integral-digits can be absent if there are fractional-digits.

,

A culture-specific thousands separator. The current culture's group separator symbol can appear in s if style includes the NumberStyles.AllowThousands flag

.

A culture-specific decimal point symbol. The current culture's decimal point symbol can appear in s if style includes the NumberStyles.AllowDecimalPoint flag.

fractional-digits

A series of digits ranging from 0 to 9 that specify the fractional part of the number. Fractional digits can appear in s if style includes the NumberStyles.AllowDecimalPoint flag.

E

The 'e' or 'E' character, which indicates that the value is represented in exponential notation. The s parameter can represent a number in exponential notation if style includes the NumberStyles.AllowExponent flag.

exponential-digits

A series of digits ranging from 0 to 9 that specify an exponent.

A string with digits only (which corresponds to the NumberStyles.None style) always parses successfully. The remaining System.Globalization.NumberStyles members control elements that may be but are not required to be present in the input string. The following table indicates how individual NumberStyles flags affect the elements that may be present in s.

NumberStyles value

Elements permitted in s in addition to digits

None

The digits element only.

AllowDecimalPoint

The . and fractional-digits elements.

AllowExponent

The s parameter can also use exponential notation. This flag by itself supports values in the form digitsEdigits; additional flags are needed to successfully parse strings with such elements as positive or negative signs and decimal point symbols.

AllowLeadingWhite

The ws element at the beginning of s.

AllowTrailingWhite

The ws element at the end of s.

AllowLeadingSign

The sign element at the beginning of s.

AllowTrailingSign

The sign element at the end of s.

AllowParentheses

The sign element in the form of parentheses enclosing the numeric value.

AllowThousands

The , element.

AllowCurrencySymbol

The $ element.

Currency

All. The s parameter cannot represent a hexadecimal number or a number in exponential notation.

Float

The ws element at the beginning or end of s, sign at the beginning of s, and the . symbol. The s parameter can also use exponential notation.

Number

The ws, sign, , and . elements.

Any

All styles, except s cannot represent a hexadecimal number.

The s parameter is parsed using the formatting information in a NumberFormatInfo object that is initialized for the current system culture. For more information, see CurrentInfo.

Ordinarily, if you pass the Double.Parse method a string that is created by calling the Double.ToString method, the original Double value is returned. However, because of a loss of precision, the values may not be equal. In addition, attempting to parse the string representation of either MinValue or MaxValue throws an OverflowException, as the following example illustrates.

   string value;

   value = Double.MinValue.ToString();
   try {
      Console.WriteLine(Double.Parse(value));
   }   
   catch (OverflowException) {
      Console.WriteLine("{0} is outside the range of the Double type.",
                        value);
   }

   value = Double.MaxValue.ToString();
   try {
      Console.WriteLine(Double.Parse(value));
   }
   catch (OverflowException) {
      Console.WriteLine("{0} is outside the range of the Double type.",
                        value);
   }
// The example displays the following output: 
//    -1.79769313486232E+308 is outside the range of the Double type. 
//    1.79769313486232E+308 is outside the range of the Double type.

If a separator is encountered in the s parameter during a parse operation, and the applicable currency or number decimal and group separators are the same, the parse operation assumes that the separator is a decimal separator rather than a group separator. For more information about separators, see CurrencyDecimalSeparator, NumberDecimalSeparator, CurrencyGroupSeparator, and NumberGroupSeparator.

The following example uses the Double.Parse(String, NumberStyles) method to parse the string representations of Double values using the en-US culture.

public static void Main()
{
   // Set current thread culture to en-US.
   Thread.CurrentThread.CurrentCulture = CultureInfo.CreateSpecificCulture("en-US");

   string value;
   NumberStyles styles;

   // Parse a string in exponential notation with only the AllowExponent flag. 
   value = "-1.063E-02";
   styles = NumberStyles.AllowExponent;
   ShowNumericValue(value, styles);

   // Parse a string in exponential notation 
   // with the AllowExponent and Number flags.
   styles = NumberStyles.AllowExponent | NumberStyles.Number;
   ShowNumericValue(value, styles);

   // Parse a currency value with leading and trailing white space, and 
   // white space after the U.S. currency symbol.
   value = " $ 6,164.3299  ";
   styles = NumberStyles.Number | NumberStyles.AllowCurrencySymbol;
   ShowNumericValue(value, styles);

   // Parse negative value with thousands separator and decimal.
   value = "(4,320.64)";
   styles = NumberStyles.AllowParentheses | NumberStyles.AllowTrailingSign |
            NumberStyles.Float; 
   ShowNumericValue(value, styles);

   styles = NumberStyles.AllowParentheses | NumberStyles.AllowTrailingSign |
            NumberStyles.Float | NumberStyles.AllowThousands;
   ShowNumericValue(value, styles);
}

private static void ShowNumericValue(string value, NumberStyles styles)
{
   double number;
   try
   {
      number = Double.Parse(value, styles);
      Console.WriteLine("Converted '{0}' using {1} to {2}.", 
                        value, styles.ToString(), number);
   }
   catch (FormatException)
   {
      Console.WriteLine("Unable to parse '{0}' with styles {1}.", 
                        value, styles.ToString());
   }
   Console.WriteLine();                           
}   
// The example displays the following output to the console: 
//    Unable to parse '-1.063E-02' with styles AllowExponent. 
//     
//    Converted '-1.063E-02' using AllowTrailingSign, AllowThousands, Float to -0.01063. 
//     
//    Converted ' $ 6,164.3299  ' using Number, AllowCurrencySymbol to 6164.3299. 
//     
//    Unable to parse '(4,320.64)' with styles AllowTrailingSign, AllowParentheses, Float. 
//     
//    Converted '(4,320.64)' using AllowTrailingSign, AllowParentheses, AllowThousands, Float to -4320.64.   

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

Date

History

Reason

May 2009

Expanded the Return Value section.

Content bug fix.

March 2009

Expanded the Remarks section.

Content bug fix.

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