C# String.IsNormalized Method

The String.IsNormalized() method in C# is used to indicate whether this string is in a particular Unicode normalization form. Unicode normalization ensures that text with the same meaning has a consistent binary representation, which is important for string comparison and text processing.

Syntax

The syntax is as follows −

public bool IsNormalized();
public bool IsNormalized(System.Text.NormalizationForm normalizationForm);

Parameters

normalizationForm − A System.Text.NormalizationForm enumeration value that specifies the Unicode normalization form to check against. The possible values are:

• FormC − Canonical Decomposition followed by Canonical Composition

• FormD − Canonical Decomposition

• FormKC − Compatibility Decomposition followed by Canonical Composition

• FormKD − Compatibility Decomposition

Return Value

Returns true if the string is normalized in the specified form; otherwise, false.

Using IsNormalized() with Default Form

When called without parameters, IsNormalized() checks for FormC normalization −

using System;

public class Demo {
   public static void Main() {
      string str1 = "Hello";
      string str2 = "World";
      
      Console.WriteLine("String 1 = " + str1);
      Console.WriteLine("String 2 = " + str2);
      
      bool res1 = str1.IsNormalized();
      Console.WriteLine("String 1 is normalized (FormC): " + res1);
      
      bool res2 = str2.IsNormalized();
      Console.WriteLine("String 2 is normalized (FormC): " + res2);
   }
}

The output of the above code is −

String 1 = Hello
String 2 = World
String 1 is normalized (FormC): True
String 2 is normalized (FormC): True

Using IsNormalized() with Specific Forms

This example demonstrates checking normalization across different Unicode forms −

using System;
using System.Text;

public class Demo {
   public static void Main() {
      string str = "Café";
      
      Console.WriteLine("String = " + str);
      Console.WriteLine("Is normalized to FormC? = " + 
         str.IsNormalized(NormalizationForm.FormC));
      Console.WriteLine("Is normalized to FormD? = " + 
         str.IsNormalized(NormalizationForm.FormD));
      Console.WriteLine("Is normalized to FormKC? = " + 
         str.IsNormalized(NormalizationForm.FormKC));
      Console.WriteLine("Is normalized to FormKD? = " + 
         str.IsNormalized(NormalizationForm.FormKD));
   }
}

The output of the above code is −

String = Café
Is normalized to FormC? = True
Is normalized to FormD? = True
Is normalized to FormKC? = True
Is normalized to FormKD? = True

Practical Example with Accented Characters

This example shows how normalization affects strings with combined characters −

using System;
using System.Text;

public class Demo {
   public static void Main() {
      // Character é can be represented as single character or e + accent
      string composed = "\u00e9";     // Single character é
      string decomposed = "\u0065\u0301";  // e + combining acute accent
      
      Console.WriteLine("Composed string: " + composed);
      Console.WriteLine("Decomposed string: " + decomposed);
      Console.WriteLine("Are they equal? " + composed.Equals(decomposed));
      
      Console.WriteLine("\nNormalization check:");
      Console.WriteLine("Composed FormC: " + composed.IsNormalized(NormalizationForm.FormC));
      Console.WriteLine("Decomposed FormC: " + decomposed.IsNormalized(NormalizationForm.FormC));
      Console.WriteLine("Composed FormD: " + composed.IsNormalized(NormalizationForm.FormD));
      Console.WriteLine("Decomposed FormD: " + decomposed.IsNormalized(NormalizationForm.FormD));
   }
}

The output of the above code is −

Composed string: é
Decomposed string: é
Are they equal? False
Normalization check:
Composed FormC: True
Decomposed FormC: False
Composed FormD: False
Decomposed FormD: True

Conclusion

The String.IsNormalized() method is essential for Unicode text processing, allowing you to check if strings are in specific normalization forms. This is crucial for proper string comparison and ensuring consistent text representation in applications dealing with international characters.