static void Main(string[] args) { try { if (args.Length == 1) { Parser calcParser = new Parser(args[0]); calcParser.parseExpression(); Console.WriteLine("Result: " + calcParser.evaluate()); } else { throw new ArgumentException("Invalid Input. Wrong number of arguments."); } } catch (ArgumentException argExc) { Console.WriteLine(argExc.Message); } catch (Exception exc) { Console.WriteLine(exc.Message); } }