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C# C# Basics (Retired) Perfect Final

Sean Brannon
Sean Brannon
596 Points
Posted by Sean Brannon
Sean Brannon
596 Points

C# Final Challenge, lost as to what i am doing wrong.

not sure what i am doing wrong on this one, i keep getting the same error and i know where it is but i just dont know how to fix it.

System.ArgumentNullException: Value cannot be null. Parameter name: String

at System.Number.StringToNumber (System.String str, System.Globalization.NumberStyles options, System.Number+NumberBuffer& number, System.Globalization.NumberFormatInfo info, System.Boolean parseDecimal) [0x00054] in /builddir/build/BUILD/mono-4.8.1/mcs/class/referencesource/mscorlib/system/number.cs:1074

at System.Number.ParseInt32 (System.String s, System.Globalization.NumberStyles style, System.Globalization.NumberFormatInfo info) [0x00014] in /builddir/build/BUILD/mono-4.8.1/mcs/class/referencesource/mscorlib/system/number.cs:745

at System.Int32.Parse (System.String s) [0x00000] in /builddir/build/BUILD/mono-4.8.1/mcs/class/referencesource/mscorlib/system/int32.cs:120

at Treehouse.CodeChallenges.Program.Main () [0x00012] in <86cdb0f446c94141914cf2255066b6ab>:0

at MonoTester.Run () [0x00095] in MonoTester.cs:86

at MonoTester.Main (System.String[] args) [0x00013] in MonoTester.cs:28

Program.cs 
using System;

namespace Treehouse.CodeChallenges
{
    class Program
    {
        static void Main()
        {
            var celebrations = 0;

            while (true)
            {
                Console.Write("Enter the number of times to print \"Yay!\": ");
                string entry = Console.ReadLine();
                int yays = int.Parse(entry);


                celebrations = celebrations + yays;
                if (celebrations <=0)
                {
                    try
                    {
                        while (celebrations < 5)
                        {
                            Console.WriteLine("Yay!");
                        }
                    }
                    catch(FormatException)
                    {
                        continue;
                    }
                }
            }
        }
    }
}
Sean Brannon
Sean Brannon
596 Points
Sean Brannon
Sean Brannon
596 Points

Ok i am still lost on what code i should be using to track the number the user enters and change that into a certain amount of Yay!

this is the code i currently have which only writes 1 Yay!

using System;

namespace Treehouse.CodeChallenges
{
    class Program
    {
        static void Main()
        {   var celebrations = 0;

            bool repeat = true;

            while(repeat)
            {
                Console.Write("Enter the number of times to print \"Yay!\": ");
                string entry = Console.ReadLine();
                int yays = int.Parse(entry);


                celebrations = celebrations + yays;
                if(celebrations >= 5)
                {
                    repeat = false;
                }
            }
             Console.WriteLine("Yay!");
        }
    }
}

as for the code Steven Parker wrote, i have no idea how im supposed to implement it. and i am also not sure which function it is (subtraction assignment or Unsubscribe) either of which i dont know how to use.

while (yays > 0)
 {
    // do something...
    yays -= 1;
 }
Steven Parker
Steven Parker
231,222 Points
Steven Parker
Steven Parker
231,222 Points

I was showing an example of a different way you might construct a loop. The "do something" comment is where the WriteLine would go.

2 Answers

Steven Parker
Steven Parker
231,222 Points
Steven Parker
Steven Parker
231,222 Points

If the input is not valid, you should print out an error message and then end, but the code shown has no error message. And if it is valid, you need to keep a count of the times you go through the loop so you can end. If you don't modify your counter inside the loop, the test will always be true and the loop will never stop.

You also have an extra outer loop that prevents the program from ending. A program conforming to the challenge instructions will prompt and accept input only one time, and will output a number of "Yay!"s or an error message depending on the validity of the input, and then it will end.

Sean Brannon
Sean Brannon
596 Points
Sean Brannon
Sean Brannon
596 Points

Thank you so much, i have fixed my code to a working level but now im lost on how to get the Console.WriteLine to write Yays! times the number the user as entered.

using System;

namespace Treehouse.CodeChallenges
{
    class Program
    {
        static void Main()
        {   var celebrations = 0;

            bool repeat = true;

            while(repeat)
            {
                Console.Write("Enter the number of times to print \"Yay!\": ");
                string entry = Console.ReadLine();
                int yays = int.Parse(entry);


                celebrations = celebrations + yays;
                if(celebrations >= 5)
                {
                    repeat = false;
                }
            }
             Console.WriteLine("Yay!");
        }
    }
}
Steven Parker
Steven Parker
231,222 Points
Steven Parker
Steven Parker
231,222 Points

Since the prompt and input should only be done once, it should not be in the loop. And while it's possible to manage your own loop control variable, it might be easier to test your repeat condition directly in the loop, something like this:

while (yays > 0) {
    // do something...
    yays -= 1;
}
Sean Brannon
Sean Brannon
596 Points
Sean Brannon
Sean Brannon
596 Points

Took me a bit to finally grasp what you wrote, but i got it. as soon as i finally realized i should move input and counts outside of the loop it clicked.