public void ModifyOperand(string commandString) { if (operationStage == OperationStage.DisplayResult) { MoveResultToFirstOperand(); } switch (commandString) { case ".": { GetCurrentOperandObject().SetHasAPoint(true); break; } case "%": { GetCurrentOperandObject().DivideBy100(); break; } case "+/-": { GetCurrentOperandObject().Invert(); break; } case "C": { FirstOperand.Reset(); SecondOperand.Reset(); ResultOperand.Reset(); operationStage = OperationStage.EnterFirstOperand; break; } } }