public static Operation CreateOperate(string operate)
        {
            Operation oper = null;

            switch (operate)
            {
            case "+":
                oper = new OperationAdd();
                break;

            case "-":
                oper = new OpeationSub();
                break;

            case "*":
                oper = new OperationMulti();
                break;

            case "/":
                oper = new OperationDiv();
                break;

            default:
                throw new Exception("Invlidate Operator");
            }
            return(oper);
        }
 public static Operation CreateOperate(string operate)
 {
     Operation oper = null;
     switch (operate)
     {
         case "+":
             oper = new OperationAdd();
             break;
         case "-":
             oper = new OpeationSub();
             break;
         case "*":
             oper = new OperationMulti();
             break;
         case "/":
             oper = new OperationDiv();
             break;
         default:
             throw new Exception("Invlidate Operator");
     }
     return oper;
 }