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Double.Parse Method (String, NumberStyles, IFormatProvider)

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

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

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

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 Float combined with AllowThousands.

provider
Type: System.IFormatProvider

An object that supplies culture-specific formatting information about s.

Return Value

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

ExceptionCondition
ArgumentNullException

s is Nothing.

FormatException

s does not represent a numeric value.

ArgumentException

style is not a NumberStyles value.

-or-

style is the NumberStyles.AllowHexSpecifier value.

OverflowException

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

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 NumberFormatInfo.PositiveInfinitySymbol, NumberFormatInfo.NegativeInfinitySymbol, or NumberFormatInfo.NaNSymbol for the culture specified by provider. 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 framed 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 provider parameter is an IFormatProvider implementation whose GetFormat method returns a NumberFormatInfo object that supplies culture-specific information used in interpreting the format of s. Typically, it is a NumberFormatInfo or CultureInfo object. If provider is Nothing or a NumberFormatInfo cannot be obtained, the formatting information for the current system culture is used.

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
   Console.WriteLine(Double.Parse(value))
Catch e As OverflowException
   Console.WriteLine("{0} is outside the range of the Double type.", _
                     value)
End Try

value = Double.MaxValue.ToString()
Try
   Console.WriteLine(Double.Parse(value))
Catch e As OverflowException
   Console.WriteLine("{0} is outside the range of the Double type.", _
                     value)
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.            

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 illustrates the use of the Parse(String, NumberStyles, IFormatProvider) method to assign several string representations of temperature values to a Temperature object.

Imports System.Globalization

Public Class Temperature
   ' Parses the temperature from a string. Temperature scale is  
   ' indicated by 'F (for Fahrenheit) or 'C (for Celcius) at the end 
   ' of the string. 
   Public Shared Function Parse(s As String, styles As NumberStyles, _
                                provider As IFormatProvider) As Temperature
      Dim temp As New Temperature()

      If s.TrimEnd(Nothing).EndsWith("'F") Then
         temp.Value = Double.Parse(s.Remove(s.LastIndexOf("'"c), 2), _
                                   styles, provider)
      Else 
         If s.TrimEnd(Nothing).EndsWith("'C") Then
            temp.Celsius = Double.Parse(s.Remove(s.LastIndexOf("'"c), 2), _
                                        styles, provider)
         Else
            temp.Value = Double.Parse(s, styles, provider)         
         End If 
      End If 
      Return temp      
   End Function  

   ' Declare private constructor so Temperature so only Parse method can 
   ' create a new instance 
   Private Sub New  
   End Sub 

   Protected m_value As Double 

   Public Property Value() As Double 
      Get 
         Return m_value
      End Get 

      Private Set
         m_value = Value
      End Set 
   End Property 

   Public Property Celsius() As Double 
      Get 
         Return (m_value - 32) / 1.8
      End Get 
      Private Set
         m_value = Value * 1.8 + 32
      End Set 
   End Property 

   Public ReadOnly Property Fahrenheit() As Double 
      Get 
         Return m_Value
      End Get    
   End Property    
End Class 

Public Module TestTemperature
   Public Sub Main
      Dim value As String 
      Dim styles As NumberStyles
      Dim provider As IFormatProvider
      Dim temp As Temperature

      value = "25,3'C"
      styles = NumberStyles.Float
      provider = CultureInfo.CreateSpecificCulture("fr-FR")
      temp = Temperature.Parse(value, styles, provider)
      Console.WriteLine("{0} degrees Fahrenheit equals {1} degrees Celsius.", _
                        temp.Fahrenheit, temp.Celsius)

      value = " (40) 'C"
      styles = NumberStyles.AllowLeadingWhite Or NumberStyles.AllowTrailingWhite _
               Or NumberStyles.AllowParentheses
      provider = NumberFormatInfo.InvariantInfo
      temp = Temperature.Parse(value, styles, provider)
      Console.WriteLine("{0} degrees Fahrenheit equals {1} degrees Celsius.", _
                        temp.Fahrenheit, temp.Celsius)

      value = "5,778E03'C"      ' Approximate surface temperature of the Sun
      styles = NumberStyles.AllowDecimalPoint Or NumberStyles.AllowThousands Or _
               NumberStyles.AllowExponent
      provider = CultureInfo.CreateSpecificCulture("en-GB") 
      temp = Temperature.Parse(value, styles, provider)
      Console.WriteLine("{0} degrees Fahrenheit equals {1} degrees Celsius.", _
                        temp.Fahrenheit.ToString("N"), temp.Celsius.ToString("N"))

   End Sub 
End Module   

.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

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, 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.

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