How to write a function that takes an integer as a parameter and calculates and returns the squared value

Question

Ahoy! I have just started methods but I am a tad confused when it comes to methods with math. First post so be nice :) I'm aware I out in NumberToSquare way too many times! Write a program that asks the user to enter a number. In your program write a function called SquareValue that takes an integer parameter and calculates the square of integer parameter and returns this squared value. Your program should take this returned square value and display it. An example of the output is: Please enter a number to square: 8 / 8 squared is: 64

What I have so far is not so comprehensible. I thought along a few different avenues and was unsure as to what to delete. Help please.

namespace SquareValue
{
    class Program
    {
        static void Main(string[] args)
        {

            int number=NumberToSquare();
            SquareValue(NumberToSquare * NumberToSquare);
            string output;

            Console.ReadKey();
        }

        public int SquareValue(NumberToSquare, NumberToSquare);
        {
            int result = NumberToSquare * NumberToSquare;

            return result;
            Console.WriteLine("{0} squared is "+result");
    }

        public int NumberToSquare()
    {
        Console.WriteLine("Please enter a number to square: ");
        int NumberToSquare = Console.ReadLine();
        return NumberToSquare;
    }

}

Answer 1

You seem very green on programming and I'm not sure SO is a place to go to learn the basics, but I'll run through what you've done and explain what's going wrong.

Your original program concept is fine but there are many issues with basic syntax. I understand you mightn't be familiar with reading compiler errors so I'll explain the errors that I see just reading through the code...

You put a ; at the end of the SquareValue(..., ...) method which teeminates the declaration so the body in braces isn't part of the method, then things go haywire later on.

You're not passing in the value captured from the NumberToSquare method...

int number=NumberToSquare();
SquareValue(NumberToSquare * NumberToSquare);

NumberToSquare isn't a defined variable so NumberToSquare * NumberToSquare can't calculate, what you'd want is number * number where `number is the value entered by the user.

Your definition of int SquareValue(NumberToSquare, NumberToSquare) expects two parameters although you haven't speified the type. It should be

int SquareValue(int NumberToSquare, int NumberToSquare)

but you have the same variable declared twice which is another error and then you aren't passing two parameters anyway. You want to multiply a number by itself therefore you only have a single source number so why declared two parameters? You need a single parameter method

int SquareValue(int NumberToSquare)

and call like this

int number=NumberToSquare();
SquareValue(number);

Now the SquareValue() method returns an int but you never capture it in the calling code and display the result in the method. Follow the idea in this app that the Main method will do all the orchestration and display, but the SquareValue() method should ONLY do a calculation and not any I/O. I'd also rename the NumberToSquare() method a as what is actually happening ... GetNumberToSquareFromUser().

And there's also a stray " before the closing bracket.

Console.WriteLine("{0} squared is " + result");

And you defined a string output variable which is never used. And your methods need to be static because main(..) is a static method, not instance. If you declare a Squaring class and instantiated it then you could call non static methods from that. Also ReadLine() returns a string which can't be assigned to an int.

And finally the result line is implicitly using String.Format behind the scenes but you haven't specified the original number for the {0} token. You could also use interpolation. You could do either of these

Console.WriteLine("{0} squared is " + result, number);
Console.WriteLine($"{number} squared is " + result);

So here's your program revised

class Program
{
    static void Main(string[] args)
    {

        int number = GetNumberToSquareFromUser();
        int result = SquareValue(number);

        Console.WriteLine("{0} squared is " + result, number);
        Console.ReadKey();
    }

    public static int SquareValue(int numberToSquare)
    {
        return numberToSquare * numberToSquare;
    }

    public static int GetNumberToSquareFromUser()
    {
        Console.WriteLine("Please enter a number to square: ");
        int NumberToSquare = int.Parse(Console.ReadLine());
        return NumberToSquare;
    }

}

I hope this help, I know it's alot to take in, but I hope you take the time to read and really understand rather than just blindly submit the revised version.

Answer 2

When writing your methods, make them reusable. When you start using a method to output to the console in addition to its primary purpose (i.e. to square a number), its re-usability becomes minimal. It is much better to keep specific code in your main method, and put sub tasks into separate methods, such as squaring a number. Now, whenever you need to square a number, you already have a perfectly good method for that.

I didn't handle the case for users entering bad input, but that can be done in the else of the TryParse if block.

static void Main(string[] args)
{
    int squredNum = 0;
    int NumberToSquare = 0;
    Console.WriteLine("Please enter a number to square: ");
    if(int.TryParse(Console.ReadLine(), out NumberToSquare))
    {
        squredNum = SquareValue(NumberToSquare);
        Console.WriteLine("{0} squared is {1}", NumberToSquare, squredNum);
    }
    Console.ReadKey();
}

static int SquareValue(int numberToSquare)
{
    return numberToSquare * numberToSquare;
}

p.s. I would not recommend using Math.Pow() to square a number. No need to kill a fly with a bazooka!

Answer 3

Here is an example of such program with robust handling:

using System;

namespace ConsoleApp1
{
    internal static class Program
    {
        private static void Main(string[] args)
        {
            while (true)
            {
                Console.WriteLine("Enter value to square or X to exit");

                var line = Console.ReadLine();
                if (line == null)
                    continue;

                if (line.Trim().Equals("X", StringComparison.InvariantCultureIgnoreCase))
                {
                    Console.WriteLine("Exitting ...");
                    break;
                }

                int result;

                if (!int.TryParse(line, out result))
                    continue;

                Console.WriteLine(result * result);
            }
        }
    }
}

See the docs online, understand each statement, write your very own program then as your teacher will likely figure out you didn't pull that solely by yourself :)

Answer 4

I see no reason to over complicate this:

public int Square(int x)
{
  return (x * x);
}

or

public int Square(int x)
{
   return Math.Pow(x,2);
}

Or just use Math.Pow as it exists with 2 as the Power Of number.