Char.IsLetter() Method in C#

The Char.IsLetter() method in C# is used to determine whether a specified Unicode character is categorized as a Unicode letter. This method returns true if the character is a letter (uppercase or lowercase), and false otherwise.

This method is particularly useful for input validation, text processing, and character classification in applications where you need to distinguish letters from numbers, symbols, or other character types.

Syntax

Following is the syntax −

public static bool IsLetter(char ch);

Parameters

• ch − The Unicode character to evaluate.

Return Value

Returns true if the character is a Unicode letter; otherwise, false.

Using Char.IsLetter() with Letters

Example

using System;

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

The output of the above code is −

Value = K
Is the value a letter? = True

Using Char.IsLetter() with Numbers

Example

using System;

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

The output of the above code is −

Value = 2
Is the value a letter? = False

Testing Multiple Character Types

Example

using System;

public class Demo {
   public static void Main() {
      char[] testChars = {'A', 'z', '5', '@', ' ', 'Ñ'};
      
      Console.WriteLine("Character\tIsLetter()");
      Console.WriteLine("-------------------------");
      
      foreach (char ch in testChars) {
         Console.WriteLine($"{ch}\t\t{Char.IsLetter(ch)}");
      }
   }
}

The output of the above code is −

Character	IsLetter()
-------------------------
A		True
z		True
5		False
@		False
 		False
Ñ		True

Conclusion

The Char.IsLetter() method is a useful utility for character validation in C#. It returns true for any Unicode character classified as a letter (both uppercase and lowercase), making it ideal for input validation and text processing scenarios.