How can I transform string to UTF-8 in C#?

As you know the string is coming in as Encoding.Default you could simply use:

byte[] bytes = Encoding.Default.GetBytes(myString);
myString = Encoding.UTF8.GetString(bytes);

Another thing you may have to remember: If you are using Console.WriteLine to output some strings, then you should also write Console.OutputEncoding = System.Text.Encoding.UTF8;!!! Or all utf8 strings will be outputed as gbk…