Char.IsNumber Method (Char)

 

Indicates whether the specified Unicode character is categorized as a number.

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

Public Shared Function IsNumber (
	c As Char
) As Boolean

Parameters

c
Type: System.Char

The Unicode character to evaluate.

Return Value

Type: System.Boolean

true if c is a number; otherwise, false.

This method determines whether a Char is of any numeric Unicode category. In addition to including digits, numbers include characters, fractions, subscripts, superscripts, Roman numerals, currency numerators, and encircled numbers. This method contrasts with the IsDigit method, which determines whether a Char is a radix-10 digit.

System_CAPS_importantImportant

The IsNumber(Char) method is not intended to determine whether a string consists of numeric characters (for example, by calling the method for each character in a string). To determine whether a string consists of numeric characters, call one of the overloads of the TryParse method (such as Int32.TryParse or Double.TryParse of an integral or floating point type.

Valid numbers are members of the UnicodeCategory.DecimalDigitNumber, UnicodeCategory.LetterNumber, or UnicodeCategory.OtherNumber category.

The IsNumber(Char) method assumes that c corresponds to a single linguistic character and checks whether that character represents a number. 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 IsNumber(Char) 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), 
                                    Char.IsNumber(ch))
Next
' The example displays the following output:
'       U+D800: False
'       U+DD07: False

The following example demonstrates IsNumber.

Module IsNumberSample
    Sub Main()
        Dim str As String
        str = "non-numeric"

        Console.WriteLine(Char.IsNumber("8"c))      ' Output: "True"
        Console.WriteLine(Char.IsNumber(str, 3))    ' Output: "False"
    End Sub
End Module

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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