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Char.IsNumber Method (String, Int32)

.NET Framework 1.1

Indicates whether the character at the specified position in a specified string is categorized as a number.

[Visual Basic]
Overloads Public Shared Function IsNumber( _
   ByVal s As String, _
   ByVal index As Integer _
) As Boolean
public static bool IsNumber(
 string s,
 int index
public: static bool IsNumber(
 String* s,
 int index
public static function IsNumber(
   s : String,
 index : int
) : Boolean;


A string.
The character position in s.

Return Value

true if the character at position index in s is a number; otherwise, false.


Exception Type Condition
ArgumentNullException s is a null reference (Nothing in Visual Basic).
ArgumentOutOfRangeException index is less than zero or greater than the last position in s.


This method determines if a Char is of any numeric Unicode category. This contrasts with IsDigit, which determines if a Char is a radix-10 digit.

Character positions in a string are indexed starting from zero.

Valid numbers are members of the following categories in UnicodeCategory: DecimalDigitNumber, LetterNumber, or OtherNumber.


[Visual Basic, C#, C++] The following sample demonstrates IsNumber.

[Visual Basic] 
Imports System

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

using System;

public class IsNumberSample {
    public static void Main() {
        string str = "non-numeric";

        Console.WriteLine(Char.IsNumber('8'));        // Output: "True"
        Console.WriteLine(Char.IsNumber(str, 3));    // Output: "False"

#using <mscorlib.dll>
using namespace System;

int main() {
   String* str = "non-numeric";

   Console::WriteLine(Char::IsNumber('8'));     // Output: "True"
   Console::WriteLine(Char::IsNumber(str, 3));  // Output: "False"

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.


Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework, Common Language Infrastructure (CLI) Standard

See Also

Char Structure | Char Members | System Namespace | Char.IsNumber Overload List | Boolean | String | IsDigit