C# to convert from utf-8 bytes to string and back.

System.Text.Encoding utf_8 = System.Text.Encoding.UTF8;

// This is our Unicode string:
string s_unicode = "abcéabc";

// Convert a string to utf-8 bytes.
byte[] utf8Bytes = System.Text.Encoding.UTF8.GetBytes(s_unicode);

// Convert utf-8 bytes to a string.
string s_unicode2 = System.Text.Encoding.UTF8.GetString(utf8Bytes);

Console.WriteLine(s_unicode2);