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I have an assignment where I have to create code to display factors and whether a number is a perfect and/or prime number. I think I have all the code right to run my program, but when I get to the last line (Console.ReadLine()) I expect to hit enter and then exit the program. Currently, when I hit enter, the program displays whether it is a prime number and/or perfect number over and over again (each time you hit enter). So basically, it executes everything after the while loop over and over again.

Keep in mind, I'm very new to C#, so some of my syntax and readability may be weird. I am only interested in answers that will help me solve the ReadLine issue. My instructors will help me with making my code more readable and organized.

Thanks for your advice! Here is my code. I commented where the ReadLine isn't closing the program:

using System;

namespace Factorizer.UI
{
    class Program
    {
        static void Main(string[] args)
        {
            string input;
            int num, i, x = 0, sum = 0;

            while (true)
            {
                Console.Write("Enter a number: ");
                input = Console.ReadLine();

                if (int.TryParse(input, out num))
                {
                    Console.Write("\nThe factors are: ");

                    for (i = 1; i <= num; i++)
                    {
                        if (num % i == 0)
                        {
                            Console.Write("{0} ", i);
                        }
                    }
                    break;
                }
                else
                {
                    Console.WriteLine("\nThat was not a valid number!\n");
                }
            }

            for (i = 1; i < num; i++)
            {
                if (num % i == 0)
                {
                    sum = sum + i;
                }
                if (sum == num)
                {
                    Console.Write("\n\n{0} is a perfect number.\n", num);
                }
                else
                {
                    Console.Write("\n\n{0} is not a perfect number.\n", num);
                }

            for (i = 2; i <= num / 2; i++)
            {
                if (num % i == 0)
                {
                    x++;
                    break;
                }
            }

            if (x == 0 && num != 1)
            {
                Console.Write("\n{0} is a prime number.", num);
            }

            else
            {
                Console.Write("\n{0} is not a prime number.", num);
            }
            Console.ReadLine(); //this isn't closing the program!
            }
        }
    }
}
  • 1
    Welcome to Stack Overflow! It looks like you need to learn to use a debugger. Please help yourself to some [complementary debugging techniques](https://ericlippert.com/2014/03/05/how-to-debug-small-programs/). If you still have issues afterwards, please feel free to come back with more details. – Joe C Nov 25 '16 at 21:09

2 Answers2

1

Console.ReadLine() is inside the for loop. Move it down after the next bracket.

Corey Berigan
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  • I do not want the program to exit automatically. I am using Console.ReadLine() to keep the program open until the user hits enter. –  Nov 25 '16 at 21:04
  • I'm not sure, but think `Console.ReadKey()` will manage to terminate program with any key pressed. See: http://stackoverflow.com/questions/11512821/how-to-stop-c-sharp-console-applications-from-closing-automatically – Reborn Nov 25 '16 at 21:08
  • If I move it down, the program runs over and over again without having to hit a button. It just automatically loops infinitely. –  Nov 25 '16 at 21:10
  • @Reborn that is what my plan is, but it is not exiting with a pressed key, it is looping back up. –  Nov 25 '16 at 21:11
  • OK! Figured it out. Moved the Console.ReadLine(); down after the next braket AND added a break; where the inside the for loop. –  Nov 25 '16 at 21:15
1

Just put Console.ReadLine(); after the for, it's inside the for block that's why it keeps printing and remove the for that you have after the while block, like this:

string input;
        int num, i, x = 0, sum = 0;

        while (true)
        {
            Console.Write("Enter a number: ");
            input = Console.ReadLine();

            if (int.TryParse(input, out num))
            {
                Console.Write("\nThe factors are: ");

                for (i = 1; i <= num; i++)
                {
                    if (num % i == 0)
                    {
                        Console.Write("{0} ", i);
                    }
                }
                break;
            }
            else
            {
                Console.WriteLine("\nThat was not a valid number!\n");
            }
        }

        /*for (i = 1; i < num; i++)
        {*/
            if (num % i == 0)
            {
                sum = sum + i;
            }
            if (sum == num)
            {
                Console.Write("\n\n{0} is a perfect number.\n", num);
            }
            else
            {
                Console.Write("\n\n{0} is not a perfect number.\n", num);
            }

            for (i = 2; i <= num / 2; i++)
            {
                if (num % i == 0)
                {
                    x++;
                    break;
                }
            }

            if (x == 0 && num != 1)
            {
                Console.Write("\n{0} is a prime number.", num);
            }

            else
            {
                Console.Write("\n{0} is not a prime number.", num);
            }
            Console.ReadLine(); //this isn't closing the program!
        //}
Christian Melendez
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