有兩種方法：

方法一:

//字串轉byte

string StringMessage = "How Are you?";

Console.WriteLine("{0}", StringMessage);

System.Text.ASCIIEncoding ASCII = new System.Text.ASCIIEncoding();

Byte[] BytesMessage = ASCII.GetBytes(StringMessage);

//byte轉字串

Byte[] BytesMessage;

System.Text.ASCIIEncoding ASCII = new System.Text.ASCIIEncoding();

String StringMessage = ASCII.GetString( BytesMessage );

方法二:

//字串轉UTF-8 byte

string StringMessage = "Hello World How Are you? Pi /u03C0 Yen /uFFE5";

System.Text.UTF8Encoding UTF8 = new System.Text.UTF8Encoding();

Byte[] BytesMessage = UTF8.GetBytes(StringMessage);

//UTF-8 byte 轉字串

Byte[] BytesMessage;

System.Text.UTF8Encoding UTF8 = new System.Text.UTF8Encoding();

String StringMessage = UTF8.GetString( BytesMessage );