C# Adding Program - Learn Syntax & More

[TheDemx27]

Just starting to learn C#. I just wrote this program to add two numbers and loops by looking up syntax etc. There HAS to be a more efficient way to do this.

using System;

    public class Program
    {
        static void Main()
        {
            bool repeat = true;
            while (repeat == true)
                {
                    string x;
                    string y;
                    int xint;
                    int yint;
                    string useranswer;


                    Console.WriteLine("Enter 'X':");
                    x = Console.ReadLine();
                    xint = int.Parse(x);
                    Console.Clear();

                    Console.WriteLine("Enter 'Y':");
                    y = Console.ReadLine();
                    yint = int.Parse(y);
                    Console.Clear();

                    int answer = xint + yint;

                    Console.WriteLine("{0} + {1} = {2}", x, y, answer);
                    Console.ReadLine();
                    
                    Console.WriteLine("Run again?: Y/N");
                    useranswer = Console.ReadLine();
                    Console.Clear();

                    if (useranswer == "y" || useranswer == "Y")
                    {
                        repeat = true;
                    }
                    else
                    {
                        repeat = false;
                    }
                }

            }

    }

 

[jim mcnamara]

You could pass X and Y from the command line.

 

[AlephZero]

That's about as good as it gets, for reading input. C# doesn't have "easy to use" functions like scanf() in C or the << operator in C++. But those easy to use functions are not much use except for toy programs, because it's very hard to catch errors in the input.

You could make the code a neater by "factoring out" the repeated code and writing your own input function, something like

int getvalue(string prompt)
{
  Console.WriteLine(prompt);
  string x = Console.ReadLine();
  Console.Clear();
  return int.Parse(x);
}
...
xint = getvalue("Enter X:");
yint = getvalue("Enter Y:");

(Note, I haven't actually tested that code!)

Your test for repeating the loop is a bit longwinded. You could write

repeat = (useranswer == "y" || useranswer == "Y");

or even

repeat = (useranswer.ToLower() == "y");

You can also make your code shorter by declaring variables when you first use them, instead of by separate statements at the top of a function, as I did in

string x = Console.ReadLine();

or even

var x = Console.ReadLine();

where "var" means "the compiler can figure out what type of variable this is, so I don't really care".

 

[Superposed_Cat]

you could just use a forms app instead of a console app which is much more efficient or
Console.WriteLine("{0} + {1} = {2}", x, y, xint+yint);
maybe that will work its been awhile since I've done a console app. get visual studio it's so superior.

 

[harborsparrow]

It's advisable to error check all inputs. You can do it like this. Once you get an input, check to see if it really is an integer:


try
{
Int.Parse(myinputstring);
}
catch (Exception ex)
{
Console.WriteLine("That was not an integer.");
}

And yes, it will probably be needful to use a goto statement, or else, use a flag to create a rather obscure loop, until you get all legal inputs.

 

[harborsparrow]

And never, ever use Int.Parse without enclosing it in a try/catch, because otherwise your program can throw an obscure error message to the user upon bad input. When I was teaching, that would earn you an instant failing grade.