Double.Parse Method (String, NumberStyles)

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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)

Syntax

'Declaration
Public Shared Function Parse ( _
    s As String, _
    style As NumberStyles _
) As Double

public static double Parse(
    string s,
    NumberStyles style
)

Parameters

• s
  Type: System.String
  A string that contains a number to convert.

• style
  Type: System.Globalization.NumberStyles
  A bitwise combination of enumeration values that indicate the style elements that can be present in s. A typical value to specify is a combination of Float combined with AllowThousands.

Return Value

Type: System.Double
A double-precision floating-point number that is equivalent to the numeric value or symbol specified in s.

Exceptions

Exception	Condition
ArgumentNullException	s is nulla null reference (Nothing in Visual Basic).
FormatException	s does not represent a number in a valid format.
OverflowException	s represents a number that is less than MinValue or greater than MaxValue.
ArgumentException	style is not a NumberStyles value. -or- style includes the AllowHexSpecifier value.

Remarks

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:

• AllowHexSpecifier

• HexNumber

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 symbol (-) or a 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. The integral-digits element can be absent if the string contains the fractional-digits element.
,	A culture-specific group 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 (scientific) 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 present, 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 integral-digits element only.
AllowDecimalPoint	The decimal point (.) and fractional-digits elements.
AllowExponent	The "e" or "E" character, which indicates 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 thousands separator (,) element.
AllowCurrencySymbol	The currency ($) element.
Currency	All elements. However, s 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 decimal point (.) symbol. The s parameter can also use exponential notation.
Number	The ws, sign, thousands separator (,) and decimal point (.) elements.
Any	All elements. However, 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.

Dim value As String

value = Double.MinValue.ToString()
Try
   outputBlock.Text += Double.Parse(value).ToString() + vbCrLf
Catch e As OverflowException
   outputBlock.Text += String.Format("{0} is outside the range of the Double type.", _
                                     value) + vbCrLf
End Try

value = Double.MaxValue.ToString()
Try
   outputBlock.Text += Double.Parse(value).ToString() + vbCrLf
Catch e As OverflowException
   outputBlock.Text += String.Format("{0} is outside the range of the Double type.", _
                                     value) + vbCrLf
End Try
' 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.            

   string value;

   value = Double.MinValue.ToString();
   try {
      outputBlock.Text += Double.Parse(value) + "\n";
   }   
   catch (OverflowException) {
      outputBlock.Text += String.Format("{0} is outside the range of the Double type.\n",
                        value);
   }

   value = Double.MaxValue.ToString();
   try {
      outputBlock.Text += Double.Parse(value) + "\n";
   }
   catch (OverflowException) {
      outputBlock.Text += String.Format("{0} is outside the range of the Double type.\n",
                        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.

Examples

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

Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
   ' Set current thread culture to en-US.
   Thread.CurrentThread.CurrentCulture = New CultureInfo("en-US")

   Dim value As String
   Dim styles As NumberStyles

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

   ' Parse a string in exponential notation
   ' with the AllowExponent and Number flags.
   styles = NumberStyles.AllowExponent Or NumberStyles.Number
   ShowNumericValue(outputBlock, 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 Or NumberStyles.AllowCurrencySymbol
   ShowNumericValue(outputBlock, value, styles)

   ' Parse negative value with thousands separator and decimal.
   value = "(4,320.64)"
   styles = NumberStyles.AllowParentheses Or NumberStyles.AllowTrailingSign _
            Or NumberStyles.Float
   ShowNumericValue(outputBlock, value, styles)

   styles = NumberStyles.AllowParentheses Or NumberStyles.AllowTrailingSign _
            Or NumberStyles.Float Or NumberStyles.AllowThousands
   ShowNumericValue(outputBlock, value, styles)
End Sub

Private Sub ShowNumericValue(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal value As String, ByVal styles As NumberStyles)
   Dim number As Double
   Try
      number = Double.Parse(value, styles)
      outputBlock.Text &= String.Format("Converted '{0}' using {1} to {2}.", _
                        value, styles.ToString(), number) & vbCrLf
   Catch e As FormatException
      outputBlock.Text &= String.Format("Unable to parse '{0}' with styles {1}.", _
                        value, styles.ToString()) & vbCrLf
   End Try
   outputBlock.Text &= vbCrLf
End Sub
' The example displays the following output:
'    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.   

public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
   // Set current thread culture to en-US.
   Thread.CurrentThread.CurrentCulture = new CultureInfo("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(outputBlock, value, styles);

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

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

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

private static void ShowNumericValue(System.Windows.Controls.TextBlock outputBlock, string value, NumberStyles styles)
{
   double number;
   try
   {
      number = Double.Parse(value, styles);
      outputBlock.Text += String.Format("Converted '{0}' using {1} to {2}.",
                        value, styles.ToString(), number) + "\n";
   }
   catch (FormatException)
   {
      outputBlock.Text += String.Format("Unable to parse '{0}' with styles {1}.",
                        value, styles.ToString()) + "\n";
   }
   outputBlock.Text += "\n";
}
// The example displays the following output:
//    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.   

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

See Also

Reference

Double Structure

Parse Overload

System Namespace

ToString

Other Resources

Parsing Numeric Strings