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C# C# Basics (Retired) Perfect Final

tmontez
tmontez
3,333 Points
Posted by tmontez
tmontez
3,333 Points

My code for this challenge works in my workspace. I get a NullReferenceException here. Why doesnt it work here?

Here is my code:

using System;

namespace Treehouse.CodeChallenges { class Program { static void Main() { while(true) { Console.Write("Enter the number of times to print \"Yay!\": "); string entry = Console.ReadLine();

             if(entry.ToLower() == "q")
             {
                break;
             }

            try
            {
                int count = int.Parse(entry);

                if(count <= 0 )
                {
                  Console.WriteLine("Enter a number greater than 0 or type \"q\" to quit.");
                  continue;
                }

                while(count > 0)
                {
                    Console.WriteLine("Yay!");
                    count -= 1;
                }
                break;

            }
            catch(FormatException)
            {
                Console.WriteLine("Invalid Input! Please enter a number greater than 0 to try again or type \"q\" to quit.");
            }
        }
        Console.WriteLine("See Ya!");
    }
}

}

Program.cs 
using System;

namespace Treehouse.CodeChallenges
{
    class Program
    {
        static void Main()
        {
            while(true)
            {
                Console.Write("Enter the number of times to print \"Yay!\": ");
                string entry = Console.ReadLine();

                 if(entry.ToLower() == "q")
                 {
                    break;
                 }

                try
                {
                    int count = int.Parse(entry);

                    if(count <= 0 )
                    {
                      Console.WriteLine("Enter a number greater than 0 or type \"q\" to quit.");
                      continue;
                    }

                    while(count > 0)
                    {
                        Console.WriteLine("Yay!");
                        count -= 1;
                    }
                    break;

                }
                catch(FormatException)
                {
                    Console.WriteLine("Invalid Input! Please enter a number greater than 0 to try again or type \"q\" to quit.");
                }
            }
            Console.WriteLine("See Ya!");
        }
    }
}

1 Answer

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

This issue comes up pretty regularly. I think the best hints are in this post from 6 months ago (nobody ever scans the forum archives). For your convenience, I'll repeat the content here, with a slight enhancement:

People often over-think this one and get too creative, and their answer is rejected for a variety of reasons (some which don't seem to make any sense).

Here are the secret "rules" you must follow for success on this one:

  • Your program must ask for and accept input ONE TIME ONLY (so no looping, an no "exit" provision)
  • If the input validates, your program will perform exactly as in Task 1
  • If the input does not validate, it will print the error message and exit
  • Validation must be done by exception catching. There are other perfectly good methods that can be used for validation, but they will not pass this challenge