Double.Parse Double.Parse Double.Parse Double.Parse Method

Definition

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

Overloads

Parse(String, NumberStyles, IFormatProvider) Parse(String, NumberStyles, IFormatProvider) Parse(String, NumberStyles, IFormatProvider) Parse(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.

Parse(String, IFormatProvider) Parse(String, IFormatProvider) Parse(String, IFormatProvider) Parse(String, IFormatProvider)

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

Parse(ReadOnlySpan<Char>, NumberStyles, IFormatProvider) Parse(ReadOnlySpan<Char>, NumberStyles, IFormatProvider) Parse(ReadOnlySpan<Char>, NumberStyles, IFormatProvider)
Parse(String) Parse(String) Parse(String) Parse(String)

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

Parse(String, NumberStyles) Parse(String, NumberStyles) Parse(String, NumberStyles) Parse(String, NumberStyles)

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

Parse(String, NumberStyles, IFormatProvider) Parse(String, NumberStyles, IFormatProvider) Parse(String, NumberStyles, IFormatProvider) Parse(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.

public:
 static double Parse(System::String ^ s, System::Globalization::NumberStyles style, IFormatProvider ^ provider);
public static double Parse (string s, System.Globalization.NumberStyles style, IFormatProvider provider);
static member Parse : string * System.Globalization.NumberStyles * IFormatProvider -> double
Public Shared Function Parse (s As String, style As NumberStyles, provider As IFormatProvider) As Double
Parameters
s
String String String String

A string that contains a number to convert.

style
NumberStyles NumberStyles NumberStyles 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
IFormatProvider IFormatProvider IFormatProvider IFormatProvider

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

Returns

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

Exceptions

s does not represent a numeric value.

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

Examples

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.

using System;
using 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 static Temperature Parse(string s, NumberStyles styles, 
                                   IFormatProvider provider)
   {                                    
      Temperature temp = new Temperature();

      if (s.TrimEnd(null).EndsWith("'F"))
      {
         temp.Value = Double.Parse(s.Remove(s.LastIndexOf((char)39), 2), 
                                   styles, provider);
      }
      else
      {
         if (s.TrimEnd(null).EndsWith("'C"))
            temp.Celsius = Double.Parse(s.Remove(s.LastIndexOf((char)39), 2), 
                                        styles, provider);
         else
            temp.Value = Double.Parse(s, styles, provider);         
      }
      return temp;      
   } 
   
   // Declare private constructor so Temperature so only Parse method can
   // create a new instance
   private Temperature()   {}

   protected double m_value;
   
   public double Value 
   {
      get { return m_value; }
      private set { m_value = value; }
   }
   
   public double Celsius
   {
      get { return (m_value - 32) / 1.8; }
      private set { m_value = value * 1.8 + 32; }
   }
   
   public double Fahrenheit
   {
      get {return m_value; }
   }      
}

public class TestTemperature
{
   public static void Main()
   {
      string value;
      NumberStyles styles;
      IFormatProvider provider;
      Temperature temp;
      
      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 | NumberStyles.AllowTrailingWhite 
               | 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 | NumberStyles.AllowThousands |
               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"));
   }
}
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   

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:

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.

Note

Any terminating NUL (U+0000) characters in s are ignored by the parsing operation, regardless of the value of the style argument.

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 null 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.

   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.
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.

See Also

Parse(String, IFormatProvider) Parse(String, IFormatProvider) Parse(String, IFormatProvider) Parse(String, IFormatProvider)

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

public:
 static double Parse(System::String ^ s, IFormatProvider ^ provider);
public static double Parse (string s, IFormatProvider provider);
static member Parse : string * IFormatProvider -> double
Public Shared Function Parse (s As String, provider As IFormatProvider) As Double
Parameters
s
String String String String

A string that contains a number to convert.

provider
IFormatProvider IFormatProvider IFormatProvider IFormatProvider

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

Returns

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

Exceptions

s does not represent a number in a valid format.

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

Examples

The following example is the button click event handler of a Web form. It uses the array returned by the HttpRequest.UserLanguages property to determine the user's locale. It then instantiates a CultureInfo object that corresponds to that locale. The NumberFormatInfo object that belongs to that CultureInfo object is then passed to the Parse(String, IFormatProvider) method to convert the user's input to a Double value.

protected void OkToDouble_Click(object sender, EventArgs e)
{
   string locale;
   double number;
   CultureInfo culture;

   // Return if string is empty
   if (String.IsNullOrEmpty(this.inputNumber.Text))
      return;

   // Get locale of web request to determine possible format of number
   if (Request.UserLanguages.Length == 0)
      return;
   locale = Request.UserLanguages[0];
   if (String.IsNullOrEmpty(locale))
      return;

  // Instantiate CultureInfo object for the user's locale
   culture = new CultureInfo(locale);

   // Convert user input from a string to a number
   try
   {
      number = Double.Parse(this.inputNumber.Text, culture.NumberFormat);
   }
   catch (FormatException)
   {
      return;
   }
   catch (OverflowException)
   {
      return;
   }
   // Output number to label on web form
   this.outputNumber.Text = "Number is " + number.ToString();
}
Protected Sub OkToDouble_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles OkToDouble.Click
   Dim locale As String
   Dim culture As CultureInfo
   Dim number As Double

   ' Return if string is empty
   If String.IsNullOrEmpty(Me.inputNumber.Text) Then Exit Sub
   
   ' Get locale of web request to determine possible format of number
   If Request.UserLanguages.Length = 0 Then Exit Sub
   locale = Request.UserLanguages(0)
   If String.IsNullOrEmpty(locale) Then Exit Sub

   ' Instantiate CultureInfo object for the user's locale
   culture = New CultureInfo(locale)

   ' Convert user input from a string to a number
   Try
      number = Double.Parse(Me.inputNumber.Text, culture.NumberFormat)
   Catch ex As FormatException
      Exit Sub
   Catch ex As Exception
      Exit Sub
   End Try

   ' Output number to label on web form
   Me.outputNumber.Text = "Number is " & number.ToString()
End Sub

Remarks

This overload of the Parse(String, IFormatProvider) method is typically used to convert text that can be formatted in a variety of ways to a Double value. For example, it can be used to convert the text that is entered by a user into an HTML text box to a numeric value.

The s parameter is interpreted using a combination of the NumberStyles.Float and NumberStyles.AllowThousands flags. The s parameter can contain NumberFormatInfo.PositiveInfinitySymbol, NumberFormatInfo.NegativeInfinitySymbol, or NumberFormatInfo.NaNSymbol for the culture specified by provider, or it can contain a string of the form:

[ws][sign]integral-digits[.[fractional-digits]][E[sign]exponential-digits][ws]

Optional elements are framed in square brackets ([ and ]). Elements that contain the term "digits" consist of a series of numeric characters ranging from 0 to 9.

Element Description
ws A series of white-space characters.
sign A negative sign symbol (-) or a positive sign symbol (+).
integral-digits A series of digits ranging from 0 to 9 that specify the integral part of the number. Runs of integral-digits can be partitioned by a group-separator symbol. For example, in some cultures a comma (,) separates groups of thousands. The integral-digits element can be absent if the string contains the fractional-digits element.
. A culture-specific decimal point symbol.
fractional-digits A series of digits ranging from 0 to 9 that specify the fractional part of the number.
E The "e" or "E" character, which indicates that the value is represented in exponential (scientific) notation.
exponential-digits A series of digits ranging from 0 to 9 that specify an exponent.

For more information about numeric formats, see the Formatting Types topic.

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 null 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.

   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.
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.

See Also

Parse(ReadOnlySpan<Char>, NumberStyles, IFormatProvider) Parse(ReadOnlySpan<Char>, NumberStyles, IFormatProvider) Parse(ReadOnlySpan<Char>, NumberStyles, IFormatProvider)

public static double Parse (ReadOnlySpan<char> s, System.Globalization.NumberStyles style = System.Globalization.NumberStyles.AllowDecimalPoint | System.Globalization.NumberStyles.AllowExponent | System.Globalization.NumberStyles.AllowLeadingSign | System.Globalization.NumberStyles.AllowLeadingWhite | System.Globalization.NumberStyles.AllowThousands | System.Globalization.NumberStyles.AllowTrailingWhite | System.Globalization.NumberStyles.Float | System.Globalization.NumberStyles.Integer, IFormatProvider provider = null);
static member Parse : ReadOnlySpan<char> * System.Globalization.NumberStyles * IFormatProvider -> double
Public Shared Function Parse (s As ReadOnlySpan(Of Char), Optional style As NumberStyles = System.Globalization.NumberStyles.AllowDecimalPoint | System.Globalization.NumberStyles.AllowExponent | System.Globalization.NumberStyles.AllowLeadingSign | System.Globalization.NumberStyles.AllowLeadingWhite | System.Globalization.NumberStyles.AllowThousands | System.Globalization.NumberStyles.AllowTrailingWhite | System.Globalization.NumberStyles.Float | System.Globalization.NumberStyles.Integer, Optional provider As IFormatProvider = null) As Double
Parameters
Returns

Parse(String) Parse(String) Parse(String) Parse(String)

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

public:
 static double Parse(System::String ^ s);
public static double Parse (string s);
static member Parse : string -> double
Public Shared Function Parse (s As String) As Double
Parameters
s
String String String String

A string that contains a number to convert.

Returns

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

Exceptions

s does not represent a number in a valid format.

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

Examples

The following example illustrates the use of the Parse(String) method.

public ref class Temperature
{
   // Parses the temperature from a string in form
   // [ws][sign]digits['F|'C][ws]
public:
   static Temperature^ Parse( String^ s )
   {
      Temperature^ temp = gcnew Temperature;
      if ( s->TrimEnd(nullptr)->EndsWith( "'F" ) )
      {
         temp->Value = Double::Parse( s->Remove( s->LastIndexOf( '\'' ), 2 ) );
      }
      else
      if ( s->TrimEnd(nullptr)->EndsWith( "'C" ) )
      {
         temp->Celsius = Double::Parse( s->Remove( s->LastIndexOf( '\'' ), 2 ) );
      }
      else
      {
         temp->Value = Double::Parse( s );
      }

      return temp;
   }

protected:
   // The value holder
   double m_value;

public:
   property double Value 
   {
      double get()
      {
         return m_value;
      }
      void set( double value )
      {
         m_value = value;
      }
   }

   property double Celsius 
   {
      double get()
      {
         return (m_value - 32.0) / 1.8;
      }
      void set( double value )
      {
         m_value = 1.8 * value + 32.0;
      }
   }
};
public class Temperature {
	// Parses the temperature from a string in form
	// [ws][sign]digits['F|'C][ws]
	public static Temperature Parse(string s) {
		Temperature temp = new Temperature();

		if( s.TrimEnd(null).EndsWith("'F") ) {
			temp.Value = Double.Parse( s.Remove(s.LastIndexOf('\''), 2) );
		}
		else if( s.TrimEnd(null).EndsWith("'C") ) {
			temp.Celsius = Double.Parse( s.Remove(s.LastIndexOf('\''), 2) );
		}
		else {
			temp.Value = Double.Parse(s);
		}

		return temp;
	}

	// The value holder
	protected double m_value;

	public double Value {
		get {
			return m_value;
		}
		set {
			m_value = value;
		}
	}

	public double Celsius {
		get {
			return (m_value-32.0)/1.8;
		}
		set {
			m_value = 1.8*value+32.0;
		}
	}
}
Public Class Temperature
    ' Parses the temperature from a string in form
    ' [ws][sign]digits['F|'C][ws]
    Public Shared Function Parse(ByVal s As String) As Temperature
        Dim temp As New Temperature()

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

    ' The value holder
    Protected m_value As Double

    Public Property Value() As Double
        Get
            Return m_value
        End Get
        Set(ByVal Value As Double)
            m_value = Value
        End Set
    End Property

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

Remarks

The s parameter can contain the current culture's NumberFormatInfo.PositiveInfinitySymbol, NumberFormatInfo.NegativeInfinitySymbol, NumberFormatInfo.NaNSymbol, or a string of 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.
sign A negative sign symbol (-) or a positive sign symbol (+). Only a leading sign can be used.
integral-digits A series of digits ranging from 0 to 9 that specify the integral part of the number. Runs of integral-digits can be partitioned by a group-separator symbol. For example, in some cultures a comma (,) separates groups of thousands. The integral-digits element can be absent if the string contains the fractional-digits element.
, A culture-specific thousands separator symbol.
. A culture-specific decimal point symbol.
fractional-digits A series of digits ranging from 0 to 9 that specify the fractional part of the number.
E The "e" or "E" character, which indicates that the value is represented in exponential (scientific) notation.
exponential-digits A series of digits ranging from 0 to 9 that specify an exponent.

The s parameter is interpreted using a combination of the NumberStyles.Float and NumberStyles.AllowThousands flags. This means that white space and thousands separators are allowed, for example, while currency symbols are not. For finer control over which style elements are permitted in s for the parse operation to succeed, call the Double.Parse(String, NumberStyles) or the Double.Parse(String, NumberStyles, IFormatProvider) method.

The s parameter is interpreted using the formatting information in a NumberFormatInfo object that is initialized for the current thread culture. For more information, see CurrentInfo. To parse a string using the formatting information of some other culture, call the Double.Parse(String, IFormatProvider) or Double.Parse(String, NumberStyles, IFormatProvider) method.

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.
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.

See Also

Parse(String, NumberStyles) Parse(String, NumberStyles) Parse(String, NumberStyles) Parse(String, NumberStyles)

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

public:
 static double Parse(System::String ^ s, System::Globalization::NumberStyles style);
public static double Parse (string s, System.Globalization.NumberStyles style);
static member Parse : string * System.Globalization.NumberStyles -> double
Public Shared Function Parse (s As String, style As NumberStyles) As Double
Parameters
s
String String String String

A string that contains a number to convert.

style
NumberStyles NumberStyles NumberStyles 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.

Returns

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

Exceptions

s does not represent a number in a valid format.

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

Examples

The following example uses the 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.   
Public Sub Main()
   ' Set current thread culture to en-US.
   Thread.CurrentThread.CurrentCulture = CultureInfo.CreateSpecificCulture("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(value, styles) 
   
   ' Parse a string in exponential notation
   ' with the AllowExponent and Number flags.
   styles = NumberStyles.AllowExponent Or 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 Or NumberStyles.AllowCurrencySymbol
   ShowNumericValue(value, styles)
   
   ' Parse negative value with thousands separator and decimal.
   value = "(4,320.64)"
   styles = NumberStyles.AllowParentheses Or NumberStyles.AllowTrailingSign _
            Or NumberStyles.Float 
   ShowNumericValue(value, styles)
   
   styles = NumberStyles.AllowParentheses Or NumberStyles.AllowTrailingSign _
            Or NumberStyles.Float Or NumberStyles.AllowThousands
   ShowNumericValue(value, styles)
End Sub

Private Sub ShowNumericValue(value As String, styles As NumberStyles)
   Dim number As Double
   Try
      number = Double.Parse(value, styles)
      Console.WriteLine("Converted '{0}' using {1} to {2}.", _
                        value, styles.ToString(), number)
   Catch e As FormatException
      Console.WriteLine("Unable to parse '{0}' with styles {1}.", _
                        value, styles.ToString())
   End Try
   Console.WriteLine()                           
End Sub
' 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.   

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:

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.

Note

Any terminating NUL (U+0000) characters in s are ignored by the parsing operation, regardless of the value of the style argument.

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.

   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.
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.

See Also

Applies to