using System;

using System.Text;

using System.Collections.Generic;

using System.Linq;

​

using NUnit.Framework;

​

//https://stackoverflow.com/questions/78409290/converting-a-c-sharp-string-to-a-hex-representation-of-its-utf8-encoded-characte

​

public static class TextHelper

{

    public static string ToUtf8HexValues(this string s)

    {

        Span<byte> span = stackalloc byte[8]; // Greater than or equal to Encoding.UTF8.GetMaxByteCount(1)

        Span<char> charSpan = stackalloc char[4]; // Greater than or equal to the max number of hex chars in a byte value

        var sb = new StringBuilder();

        foreach (var rune in s.EnumerateRunes())

        {

            if (sb.Length > 0)

                sb.Append(' ');

            for (int i = 0, length = rune.EncodeToUtf8(span); i < length; i++)

                if (span[i].TryFormat(charSpan, out var n, "X"))

                    sb.Append(charSpan.Slice(0, n));

        }

        return sb.ToString();

    }

}

​

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine($"Encoding.UTF8.GetMaxByteCount(1) = {Encoding.UTF8.GetMaxByteCount(1)}\n");

        var s = "$£€𐍈".ToUtf8HexValues();

        Console.WriteLine(s);

        Assert.That(s == "24 C2A3 E282AC F0908D88");

    }

}