c# method to get the number of bytes of a string

class StringOP
    {
        /// <summary>
/// Get the actual length (number of bytes) of the mixed Chinese and English string
        /// </summary>
/// <param name="str">To get the string of length</param>
/// <returns>The actual length value of the string (number of bytes)</returns>
        public int getStringLength(string str)
        {
            if (())
                return 0;
            int strlen = 0;
            ASCIIEncoding strData = new ASCIIEncoding();
//Convert string to ASCII encoded byte numbers
            byte[] strBytes = (str);
            for (int i = 0; i <= - 1; i++)
            {
if (strBytes[i] == 63) //The Chinese will be encoded as ASCII encoding 63, that is, the "?" number
                    strlen++;
                strlen++;
            }
            return strlen;
        }
    }

    class TestMain
    {
        static void Main()
        {
            StringOP sop = new StringOP();
string str = "I Love China!I Love Beijing!";
            int iLen = (str);
(The number of bytes of "string" + str + " is: " + ());
            ();
        }
    }