Sentinal Controled loop

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March 7th, 2013, 10:00 PM

devdoc345

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Sentinal Controled loop

So i am writing a console based app useing a sentinal controled loop but when i write a while statment with
while (inValue != "xxx") ;
Nothing runs
but
while (inValue == "xxx") ;
This does work but its not what i want to do.
The question is Why is it not running while useing != ?
Here is the code :

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CH_6_ex3
{
    class Ch6_ex3
    {
        static void Main(string[] args)
        {
            // declrations
            int totalAvg = inputAvg();
            displayAvg(totalAvg);
            
        }

        public static int inputAvg()
        {

            //declrations
            string inValue = "";
            int score;
            int count = 0;

            // sentinal control loop
            while (inValue != "-99") ;

            // count is for the average count
            count++;

            // input
            Console.WriteLine("Please Enter score 0 - 100, Enter xxx to quit");
            inValue = Console.ReadLine();
            score = Convert.ToInt32(inValue);

            // tempary test to make sure it is working
            Console.WriteLine("This is your score {0}", score);

            // return statment
            return score / (count * 100);
        }
        public static void displayAvg(int totalAvg)
        {

            // output / bool to determine grade
            if (totalAvg > 89)
                Console.WriteLine("Your current grade is an A and your average score is: " + totalAvg);
            else if (totalAvg > 79)
                Console.WriteLine("Your current grade is a B and your average score is: " + totalAvg);
            else if (totalAvg > 69)
                Console.WriteLine("Your current grade is a C and your average score is: " + totalAvg);
            else if (totalAvg > 59)
                Console.WriteLine("Your current grade is a D and your average score is: " + totalAvg);
            else
                Console.WriteLine("Your current grade is a F and your average score is: " + totalAvg);   
        }
    }
}

March 7th, 2013, 11:50 PM

salem

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Please edit your post and put [code][/code] tags around your code.
Copy again from your code editor so indentation is preserved.

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March 8th, 2013, 12:15 AM

devdoc345

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fixed

March 8th, 2013, 12:19 AM

salem

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> while (inValue != "-99") ;
What's that ; doing at the end?
It seems to me, you've written

Code:

while (inValue != "-99")  {
    // do nothing at all
}

If the condition is false, nothing happens.
If the condition is true, then that's where it will remain stuck for the rest of time.

Replace the ; with { } around the code you want to loop.

March 8th, 2013, 12:51 AM

devdoc345

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Ok so i got that fixed, now i have this error, where it says score is an unassiqned variable

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CH_6_ex3
{
    class Ch6_ex3
    {
        static void Main(string[] args)
        {
            // declrations
            //int totalAvg = inputAvg();
            //displayAvg(totalAvg);
            
        }

        public static int inputAvg()
        {

            //declrations
            string inValue = "";
            int score;
            int count = 0;
            int avg;

            // sentinal control loop
            while (inValue != "-99")
            {
                // count is for the average count
                count++;

                // input
                Console.WriteLine("Please Enter score 0 - 100, Enter -99 to quit");
                inValue = Console.ReadLine();
                score = Convert.ToInt32(inValue);
            }
            avg = score / (count * 100);
            return avg;
        }
        public static void displayAvg(int totalAvg)
        {

            // output / bool to determine grade
            if (totalAvg > 89)
                Console.WriteLine("Your current grade is an A and your average score is: " + totalAvg);
            else if (totalAvg > 79)
                Console.WriteLine("Your current grade is a B and your average score is: " + totalAvg);
            else if (totalAvg > 69)
                Console.WriteLine("Your current grade is a C and your average score is: " + totalAvg);
            else if (totalAvg > 59)
                Console.WriteLine("Your current grade is a D and your average score is: " + totalAvg);
            else
                Console.WriteLine("Your current grade is a F and your average score is: " + totalAvg);   
        }
    }
}

March 8th, 2013, 08:42 AM

bullet

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Join Date: Jan 2004

Location: Mobile, Alabama

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In inputAvg, you define score, and don't give it an initial value. You set it's value inside the while loop, but it's possible the body of the loop won't be executed.

Sentinal Controled loop

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