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C# C# Basics (Retired) Perfect Final

Pongpon Tienthong
Pongpon Tienthong
1,784 Points
Posted by Pongpon Tienthong
Pongpon Tienthong
1,784 Points

System.NullReferenceException

I run this code and the error "System.NullReferenceException" occured. Have any ideas?

Program.cs 
using System;

namespace Treehouse.CodeChallenges
{
    class Program
    {
        static void Main()
        {
            int present=1;
            while(true)
            {
                Console.Write("Enter the number of times to print \"Yay!\": ");
                var entry=Console.ReadLine();
                if(entry.ToLower()=="quit")
                {
                    break;
                }    
                try
                {    
                    var times=int.Parse(entry);

                    while(true)
                    {    
                        if(present<=times)
                        {
                            Console.WriteLine("Yay!");
                            present+=1;
                        }
                        else
                        {
                            break;
                        }
                    }
                    break;
                }
                catch(FormatException)
                {
                    Console.WriteLine("You must enter a whole number.");
                    continue;
                }

            }


        }
    }
}

1 Answer

Steven Parker
Steven Parker
231,108 Points
Steven Parker
Steven Parker
231,108 Points

:point_right: Your program "works", but deviates from the instructions.

This is a great example of how something that works (will compile an run) might not be what was asked for (satisfies the requirements). This has been a topic of many previous questions, but I'll repost the info here:

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
  • 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

It looks like you have an extra loop that is violating the first and third "rule".