Char.IsDigit Method (String, Int32)

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

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)


Public Shared Function IsDigit ( _
    s As String, _
    index As Integer _
) As Boolean
public static bool IsDigit(
    string s,
    int index


Return Value

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


Exception Condition

s is nullNothingnullptra null reference (Nothing in Visual Basic).


index is less than zero or greater than the last position in s.


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.


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

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0


Windows Phone

See Also


Char Structure

IsDigit Overload

System Namespace