Char.ConvertToUtf32(String, Int32) Method in C#

The Char.ConvertToUtf32(String, Int32) method in C# is used to convert the value of a UTF-16 encoded character or surrogate pair at a specified position in a string into a Unicode code point. This method is particularly useful when working with Unicode characters that may be represented as surrogate pairs in UTF-16 encoding.

Syntax

Following is the syntax −

public static int ConvertToUtf32(string s, int index);

Parameters

• s − The string that contains a character or surrogate pair.

• index − The index position of the character or surrogate pair in the string.

Return Value

Returns the 21-bit Unicode code point represented by the character or surrogate pair at the specified position in the string.

Using ConvertToUtf32 with Basic Characters

Example

using System;

public class Demo {
   public static void Main() {
      int utf = 0x046;
      string str = Char.ConvertFromUtf32(utf);
      Console.WriteLine("Character = " + str);
      
      int res = Char.ConvertToUtf32(str, 0);
      Console.WriteLine("Unicode Code Point = 0x{0:X}", res);
   }
}

The output of the above code is −

Character = F
Unicode Code Point = 0x46

Using ConvertToUtf32 with Different Characters

Example

using System;

public class Demo {
   public static void Main() {
      string text = "Hello World!";
      
      for (int i = 0; i < text.Length; i++) {
         int codePoint = Char.ConvertToUtf32(text, i);
         Console.WriteLine("Character '{0}' at index {1} = U+{2:X4}", 
                          text[i], i, codePoint);
      }
   }
}

The output of the above code is −

Character 'H' at index 0 = U+0048
Character 'e' at index 1 = U+0065
Character 'l' at index 2 = U+006C
Character 'l' at index 3 = U+006C
Character 'o' at index 4 = U+006F
Character ' ' at index 5 = U+0020
Character 'W' at index 6 = U+0057
Character 'o' at index 7 = U+006F
Character 'r' at index 8 = U+0072
Character 'l' at index 9 = U+006C
Character 'd' at index 10 = U+0064
Character '!' at index 11 = U+0021

Using ConvertToUtf32 with Surrogate Pairs

Example

using System;

public class Demo {
   public static void Main() {
      // High surrogate pair example (Emoji)
      int emojiCodePoint = 0x1F600; // Grinning face emoji
      string emoji = Char.ConvertFromUtf32(emojiCodePoint);
      Console.WriteLine("Emoji: " + emoji);
      Console.WriteLine("String length: " + emoji.Length);
      
      // Convert back to code point
      int result = Char.ConvertToUtf32(emoji, 0);
      Console.WriteLine("Code point: U+{0:X}", result);
      Console.WriteLine("Original matches result: " + (emojiCodePoint == result));
   }
}

The output of the above code is −

Emoji: ?
String length: 2
Code point: U+1F600
Original matches result: True

Conclusion

The Char.ConvertToUtf32(String, Int32) method converts UTF-16 encoded characters or surrogate pairs at a specified string index into Unicode code points. This method is essential when working with Unicode text that may contain characters beyond the Basic Multilingual Plane, ensuring proper character handling in internationalized applications.