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Convert.ToDouble Method (String, IFormatProvider)

Converts the specified string representation of a number to an equivalent double-precision floating-point number, using the specified culture-specific formatting information.

Namespace:  System
Assemblies:   System.Runtime.Extensions (in System.Runtime.Extensions.dll)
  mscorlib (in mscorlib.dll)

Public Shared Function ToDouble ( _
	value As String, _
	provider As IFormatProvider _
) As Double


Type: System.String

A string that contains the number to convert.

Type: System.IFormatProvider

An object that supplies culture-specific formatting information.

Return Value

Type: System.Double
A double-precision floating-point number that is equivalent to the number in value, or 0 (zero) if value is Nothing.


value is not a number in a valid format.


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

The return value is the result of invoking the Double.Parse method on value.

provider is an IFormatProvider instance that obtains a NumberFormatInfo object. The NumberFormatInfo object provides culture-specific information about the format of value. If provider is Nothing, the NumberFormatInfo for the current culture is used.

If you prefer not to handle an exception if the conversion fails, you can call the Double.TryParse method instead. It returns a Boolean value that indicates whether the conversion succeeded or failed.

The following example converts string representations of Double values with the ToDouble method, using an IFormatProvider object.

Imports System.Globalization

Module Example
    Sub Main()
        ' Create a NumberFormatInfo object and set some of its properties. 
        Dim provider As New NumberFormatInfo() 
        provider.NumberDecimalSeparator = ","
        provider.NumberGroupSeparator = "."
        provider.NumberGroupSizes = { 3 }

        ' Define an array of numeric strings to convert. 
        Dim values() As String = { "123456789", "12345.6789", "12345,6789", 
                                   "123,456.789", "123.456,789", 
                                   "123,456,789.0123", "123.456.789,0123" }

        Console.WriteLine("Default Culture: {0}", 
        Console.WriteLine("{0,-22} {1,-20} {2,-20}", "String to Convert",
                          "Default/Exception", "Provider/Exception")
        ' Convert each string to a Double with and without the provider. 
        For Each value In values
           Console.Write("{0,-22} ", value)
              Console.Write("{0,-20} ", Convert.ToDouble(value))
           Catch e As FormatException
              Console.Write("{0,-20} ", e.GetType().Name)
           End Try 
              Console.WriteLine("{0,-20} ", Convert.ToDouble(value, provider))
           Catch e As FormatException
              Console.WriteLine("{0,-20} ", e.GetType().Name)
           End Try 
    End Sub  
End Module  
' The example displays the following output: 
'       Default Culture: en-US 
'       String to Convert      Default/Exception    Provider/Exception 
'       123456789              123456789            123456789 
'       12345.6789             12345.6789           123456789 
'       12345,6789             123456789            12345.6789 
'       123,456.789            123456.789           FormatException 
'       123.456,789            FormatException      123456.789 
'       123,456,789.0123       123456789.0123       FormatException 
'       123.456.789,0123       FormatException      123456789.0123

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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