Char.IsNumber Method (String, Int32) (System)

.NET Framework Class Library

Char..::.IsNumber Method (String, Int32)

Updated: October 2008

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

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

Syntax

Visual Basic (Declaration)

Public Shared Function IsNumber ( _
    s As String, _
    index As Integer _
) As Boolean

Visual Basic (Usage)

Dim s As String
Dim index As Integer
Dim returnValue As Boolean

returnValue = Char.IsNumber(s, index)

public static bool IsNumber(
    string s,
    int index
)

Visual C++

public:
static bool IsNumber(
    String^ s, 
    int index
)

JScript

public static function IsNumber(
    s : String, 
    index : int
) : boolean

Parameters

s: Type: System..::.String
A string.

index: Type: System..::.Int32
The character position in s.

Return Value

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

Exceptions

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

Remarks

This method determines if a Char is of any numeric Unicode category. In addition to digits, numbers include characters, fractions, subscripts, superscripts, Roman numerals, currency numerators, and encircled numbers. This method contrasts with the IsDigit method, 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 UnicodeCategory..::.DecimalDigitNumber, UnicodeCategory..::.LetterNumber, or UnicodeCategory..::.OtherNumber categories.

Examples

The following code example 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"
    }
}

Visual C++

using namespace System;
int main()
{
   String^ str =  "non-numeric";
   Console::WriteLine( Char::IsNumber( '8' ) ); // Output: "True"
   Console::WriteLine( Char::IsNumber( str, 3 ) ); // Output: "False"
}

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

Version Information