public double Evaluate() { double x = leftOperand.Evaluate(); double y = rightOperand.Evaluate(); if (operationChar == '+') { return(x + y); } if (operationChar == '-') { return(x - y); } if (operationChar == '*') { return(x * y); } if (operationChar == '/') { return(x / y); } throw new Exception("Unknown Operation!"); }