Trying to create user defined function `LIKE` using SQLite

Question

I am (trying to) using the sqlite-net-pcl package version 1.8.116, to create a user defined function in C#.

I tried to start simple by creating a function to reverse a string, like REVERSE

When i try the query: SELECT 1,'abc','def', I am expecting the output to be: 1:abc:fed

But the output is: 0:abc:System.Char[], So I must have done something wrong...

Can anyone give a tip? because I am pretty clueless right now... 😉

My code:

SQLiteConnection db = new SQLiteConnection("test.db");

// https://sqlite.org/c3ref/create_function.html
sqlite3 dbhandle = db.Handle;
string function = "myReverse";
int narg = 1;
int eTextRep = SQLitePCL.raw.SQLITE_UTF8 | SQLitePCL.raw.SQLITE_DETERMINISTIC;

int ok = SQLitePCL.raw.sqlite3_create_function(dbhandle, function, narg, eTextRep, myReverse);
//Console.WriteLine($"OK:{ok}");

SQLiteCommand cmd = db.CreateCommand("SELECT 1 as id, 'abc' as t, myReverse('def') as revt");
var result = cmd.ExecuteQuery<Record>();
Console.WriteLine($"{result[0].id}:{result[0].t}:{result[0].revt}");

and:

static void myReverse(sqlite3_context ctx, object user_data, sqlite3_value[] args)
{
    SQLitePCL.utf8z utf8z = raw.sqlite3_value_text(args[0]);
    string input = utf8z.utf8_to_string();
    //Console.WriteLine($"INPUT:{input}");  // This shows INPUT:def
    char[] charArray = input.ToCharArray();
    Array.Reverse(charArray);
    //raw.sqlite3_result_text(ctx, utf8z.FromString(charArray.ToString())); // see: comments...
    raw.sqlite3_result_text(ctx, utf8z.FromString(new string(charArray)));
}

Record:

    public class Record
    {
        public int id { get; set; }
        public string t { get; set; }
        public string revt { get; set; }
    }

Above was my first try, finally I would like to have an implementation of the function LIKE, like is mentioned in paragraph 5 "The infix LIKE operator is implemented by calling the application-defined SQL functions"

Currently returning a string is working, but I am looking for something like raw.sqlite3_result_boolean, or raw.sqlite3_result_logical, because the return value for the function LIKE is a boolean.