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Char.GetNumericValue Method (Char)

Converts the specified numeric Unicode character to a double-precision floating point number.

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

Public Shared Function GetNumericValue ( _
	c As Char _
) As Double


Type: System.Char
The Unicode character to convert.

Return Value

Type: System.Double
The numeric value of c if that character represents a number; otherwise, -1.0.

The c parameter must be the Char representation of a numeric value. For example, if c is "5", the return value is 5. However, if c is "z", the return value is -1.0.

A character has an associated numeric value if and only if it is a member of one of the following UnicodeCategory categories: DecimalDigitNumber, LetterNumber, or OtherNumber.

The GetNumericValue method assumes that c corresponds to a single linguistic character and checks whether that character can be converted to a decimal digit. However, some numbers in the Unicode standard are represented by two Char objects that form a surrogate pair. For example, the Aegean numbering system consists of code points U+10107 through U+10133. The following example uses the ConvertFromUtf32 method to instantiate a string that represents AEGEAN NUMBER ONE. As the output from the example shows, the GetNumericValue method returns false if it is passed either a high surrogate or a low surrogate of this character.

Dim utf32 As Integer = &h10107       ' AEGEAN NUMBER ONE
Dim surrogate As String = Char.ConvertFromUtf32(utf32)
For Each ch In surrogate
   Console.WriteLine("U+{0:X4}: {1}    ", Convert.ToUInt16(ch), 
' The example displays the following output:
'       U+D800: -1
'       U+DD07: -1

The following example demonstrates GetNumericValue.

Module GetNumericValueSample
    Sub Main()
        Dim str As String
        str = "input: 1"

        Console.WriteLine(Char.GetNumericValue("8"c))       ' Output: "8"
        Console.WriteLine(Char.GetNumericValue(str, 7))     ' Output: "1"
    End Sub
End Module

.NET Framework

Supported in: 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

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.