//字符转ASCII码：

public static int Asc(string character)

{

if (character.Length == 1)

{

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

int intAsciiCode = (int)asciiEncoding.GetBytes(character)[0];

return (intAsciiCode);

}

else

{

throw new Exception("Character is not valid.");

}

}

ASCII码转字符：

public static string Chr(int asciiCode)

{

if (asciiCode >= 0 && asciiCode <= 255)

{

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

byte[] byteArray = new byte[] { (byte)asciiCode };

string strCharacter = asciiEncoding.GetString(byteArray);

return (strCharacter);

}

else

{

throw new Exception("ASCII Code is not valid.");

}

}

//另一种写法

string str="abcd";

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