C# Left、Right' Mid 都可以用

        public string  StrLeft(string s, int length)
        {
            return s.Substring(0, length);
        }

        public string StrRigth(string s, int length)
        {
            return s.Substring(s.Length - length);
        }

        public string StrMid(string s, int start, int length)
        {
            return s.Substring(start, length);
        }

str = "123456789"
Left = str.substring(0,2) = "12"
Rigth = str.substring(str.length -2) = "89"
Mid = strsubstring(2,2) = "34" 

using Microsoft.VisualBasic;
Strings.Right("aaaaa",2);