How to do this in C#?

Yes,I see. Thanks!^_^

Maybe the int values in my sample should still be a char. But then you'll need to convert the values with Convert.ToChar()

think it should be this. public static string PackData(string strInput) { int nLength = strInput.Length + 2; int b = 0x03; int zero = 0x00; string strReturned = string.Format("{0}{1}", nLength, b); strReturned += strInput; for(int i = 0;i<(32 - nLength); i++) { strReturned += zero; } return strReturned; }