Convert string with unicode characters to hexadecimal with a specific format in c#

Question

I am working with a third party for sending SMS messages. The information is sent to them via HTTPS, in a SOAP envelope.

In case the text contains Unicode characters, the DataCoding needs to be set to 2 (which is Unicode) and the text, from what I understand, needs to be sent in a certain format. This format is a NCR (numeric character reference) in hexadecimal with the "&#xHHHH;" format for each unicode character.

I am not very familiar with SOAP and this format, how can that conversion be done on a string containing both Ascii and Unicode characters?

Answer 1

The following might solve your encoding task:

using System;
using System.Text;

public class Test
{
    public static void Main()
    {
        string encoded = 
            ncrEncode("My string with äöüÄÖÜß");
            
        Console.WriteLine(encoded);
    }
    
    public static string ncrEncode(string s)
    {
        StringBuilder sb = new();
        
        foreach(char c in s)
        {
            uint u = (uint)c;
            if (u > 127)
            {
                sb.Append($"&#x{u.ToString("X4")}");
            }
            else
            {
                sb.Append(c);
            }
        }
        
        return sb.ToString();
    }

    public static string ncrEncodeLinq(string s)
    {
       return string.Join("", 
       s.Select(c => (uint)c < 128 ? $"{c}" : $"&#x{(uint)c:X4}"));
    }
}

The string to be encoded is looped through character by character. Characters with codes bigger than 127 are appended as hex string.

For the fun of it, I have sequeezed the function into a one-liner.