Char.IsDigit() Method in C#

The Char.IsDigit() method in C# determines whether a specified Unicode character is categorized as a decimal digit. This method is useful for validating input, parsing strings, and filtering numeric characters from text.

Syntax

Following is the syntax for the Char.IsDigit() method −

public static bool IsDigit(char ch);

Parameters

• ch − The Unicode character to evaluate.

Return Value

Returns true if the character is a decimal digit; otherwise, false.

Using Char.IsDigit() with Different Characters

Example 1 - Testing Non-Digit Characters

using System;

public class Demo {
   public static void Main() {
      bool res;
      char val = 'g';
      Console.WriteLine("Value = " + val);
      res = Char.IsDigit(val);
      Console.WriteLine("Is the value a digit? = " + res);
   }
}

The output of the above code is −

Value = g
Is the value a digit? = False

Example 2 - Testing Digit Characters

using System;

public class Demo {
   public static void Main() {
      bool res;
      char val = '2';
      Console.WriteLine("Value = " + val);
      res = Char.IsDigit(val);
      Console.WriteLine("Is the value a digit? = " + res);
   }
}

The output of the above code is −

Value = 2
Is the value a digit? = True

Testing Multiple Characters

Example

using System;

public class Demo {
   public static void Main() {
      char[] testChars = {'5', 'A', '@', '9', ' ', '0'};
      
      Console.WriteLine("Character\tIs Digit?");
      Console.WriteLine("-------------------");
      
      foreach (char ch in testChars) {
         bool isDigit = Char.IsDigit(ch);
         Console.WriteLine($"'{ch}'\t\t{isDigit}");
      }
   }
}

The output of the above code is −

Character	Is Digit?
-------------------
'5'		True
'A'		False
'@'		False
'9'		True
' '		False
'0'		True

Common Use Cases

• Input validation − Checking if user input contains only numeric characters.

• String parsing − Extracting numeric characters from mixed text.

• Data filtering − Separating digits from non-digit characters in processing operations.

Conclusion

The Char.IsDigit() method provides a reliable way to check if a character represents a decimal digit (0-9). It returns true for digit characters and false for all other characters, making it essential for character validation and text processing tasks.