字符串和字节互换

转换为默认编码格式：
string类型转成byte[]：

byte[] byteArray = System.Text.Encoding.Default.GetBytes ( str );

byte[]转成string：

string str = System.Text.Encoding.Default.GetString ( byteArray );

方法一:
//字符串转byte
string StringMessage = "How Are you?";

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

System.Text.ASCIIEncoding ASCII = new System.Text.ASCIIEncoding();
Byte[] BytesMessage = ASCII.GetBytes(StringMessage);
//byte转字符串
Byte[] BytesMessage;

System.Text.ASCIIEncoding ASCII = new System.Text.ASCIIEncoding();
String StringMessage = ASCII.GetString( BytesMessage );

方法二:
//字符串转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 转字符串

Byte[] BytesMessage;

System.Text.UTF8Encoding UTF8 = new System.Text.UTF8Encoding();
String StringMessage = UTF8.GetString( BytesMessage );