C# C# Basics (Retired) Perfect Wrap Up

Michael Apps
Michael Apps
4,907 Points

Arithmetic Calculator

Hi

I am having a go at the Arithmetic Calculator exercise at the end of the C# Basics course. I am really struggling to figure out how it is that you can have the user input the operator and then use it in the calculation. I've google'd to no avail.

Any help would be appreciated. Thank you.

3 Answers

Steven Parker
Steven Parker
176,576 Points

You might not use it directly. But if you were to input an operator symbol as a string, you could then test that string against a set of literal strings that represent operations your program can do, and perform that operation when you have a match.

Does that help?

Michael Apps
Michael Apps
4,907 Points

Hi, thanks for the reply Steven. Not really, sorry (just started learning a few days ago).

Here is where I am so far. I know things have been repeated where there is probably a much more efficient way of doing it but I'm just trying to use what has been taught in the course so far.

I am stuck figuring out how to make var b the operator and then use it to get runningTotal. Apologies if I am going about it completely wrong .

using System;

namespace MikeCode
{
  class Arithmatic
  {
    static void Main()
    {      
      var runningTotal = 0.0;

      while(true)
      {       
        //Prompt the user for a number.
        Console.WriteLine("Enter a number");
        var a = Console.ReadLine();

        if (a.ToLower() == "quit")
        {
          break;
        }

        else 
        {
          double.Parse(a);
        }

        //Prompt the user for an operation (+ - / *).
        Console.WriteLine("Enter an operator");
        var b = Console.ReadLine();

        if (b.ToLower() == "quit")
        {
          break;
        }

        //Prompt the user for another number.
        Console.WriteLine("Enter another number");
        var c = Console.ReadLine();

        if (c.ToLower() == "quit")
        {
          break;
        }

        else 
        {
          double.Parse(c);
        }

        //Perform the operation.
        runningTotal = a b c;

        //Print the result to the screen.
        Console.WriteLine(runningTotal);

        //Repeat until the user types in “quit” at any of the prompts.
      }
      Console.WriteLine("GoodBye!");
    }
  }
}
Steven Parker
Steven Parker
176,576 Points

You'll need an assignment to save the results of your numeric conversions so you can use them later:

          a = double.Parse(a);

Be sure to something similar with "c". Then applying the hint I gave you before:

        //Perform the operation.
        if (b == '+') {
            runningTotal = a + c;
        }
        else if (b == '-') {
            runningTotal = a - c;
        }
        // etc...
Michael Apps
Michael Apps
4,907 Points

Thank you Steven, that's a big help.

Hi, May I ask why you're doing a double.Parse(a)? I don't quite understand that part.

Thanks.

Steven Parker
Steven Parker
176,576 Points

The "double.Parse" function converts a string made up of digits (and optional decimal point) into a number. This is necessary to be able to perform math on it.