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Char.IsDigit Method (String, Int32)

Microsoft Silverlight will reach end of support after October 2021. Learn more.

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

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

Syntax

'Declaration
Public Shared Function IsDigit ( _
    s As String, _
    index As Integer _
) As Boolean

public static bool IsDigit(
    string s,
    int index
)

Parameters

Return Value

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

Exceptions

Exception Condition
ArgumentNullException

s is nulla 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 a radix-10 digit. This contrasts with IsNumber, which determines if a Char is of any numeric Unicode category. Numbers include characters such as fractions, subscripts, superscripts, Roman numerals, currency numerators, encircled numbers, and script-specific digits.

Character positions in a string are indexed starting from zero.

Valid digits are members of the UnicodeCategory.DecimalDigitNumber category.

Examples

The following example demonstrates IsDigit.


Module Example

   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      Dim ch8 As Char
      ch8 = "8"c

      outputBlock.Text &= Char.IsDigit(ch8) & vbCrLf                    ' Output: "True"
      outputBlock.Text += String.Format(Char.IsDigit("sample string", 6)) & vbCrLf     ' Output: "False"

   End Sub

End Module

using System;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      char ch = '8';

      outputBlock.Text += Char.IsDigit(ch) + "\n";          // Output: "True"
      outputBlock.Text += Char.IsDigit("sample string", 7) + "\n";  // Output: "False"
   }
}

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.