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Thread: Whats wrong with my looping?

  1. #1
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    Default Whats wrong with my looping?

    import java.io.*;
       public class dowhile
       {
          public static void main(String[] args)
          {
     
           int START = 0;
           int END = 0;
           int STEP = 0;
           String input = "";
           char a = 'y';
     
                   BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
     
     
     
     
      do{     
     
       try{
             System.out.print("Input Starting number: ");
             input = in.readLine();
             START = Integer.parseInt(input);
     
             System.out.print("Input Ending number: ");
             input = in.readLine();
             END = Integer.parseInt(input);
     
             System.out.print("Input Step (interval): ");
             input = in.readLine();
             STEP = Integer.parseInt(input);
          }catch(IOException e)
           {System.out.println("Error");}
     
     
        if( START >= END )
        System.out.println("Starting Should be lesser than the ending number");
     
        if( STEP < 1 )
        System.out.println("Step should be greater than 0");
     
         do{
          System.out.println( START );
     
           START = START + STEP;
     
         }while( START < END && STEP > 0);
     
         try{
         System.out.print("Try again? Y/N: ");
         input = in.readLine();
         a = input.charAt(0); }
         catch(IOException e)
        {System.out.println("Error");}
     
         if(a != 'y' || a != 'Y' || a != 'n' || a != 'N'){
         do{ System.out.println("Enter Y or N only");  
         try{
         System.out.print("Try again? Y/N: ");
         input = in.readLine();
         a = input.charAt(0); }
         catch(IOException e)
        {System.out.println("Error");}
         }while(a != 'y' || a != 'Y' || a != 'n' || a != 'N');}
     
     
     
     
        }while(a == 'y' || a == 'Y');
     
     
    }
    }



    Its been driving me carzy help pls
    Last edited by copeg; August 21st, 2010 at 01:58 PM. Reason: Please use the code tags


  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: Whats wrong with my looping?

    What are the expected outputs, and what outputs are you actually getting?

  3. #3
    Administrator copeg's Avatar
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    Default Re: Whats wrong with my looping?

    Check your logic in evaluating the yes/no entries: they will always evaluate to true regardless of the entry and result in an infinite loop.

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: Whats wrong with my looping?

    An easy way to see what the results of a large condition like you are using is to print it:
    System.out.println("cond=" + (a != 'y' || a != 'Y' || a != 'n' || a != 'N'));

    Put the above just before the while() statement.

    Then you can work with your input and the way the above condition is coded to get the desired result.

  5. #5
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    Default Re: Whats wrong with my looping?

    Quote Originally Posted by helloworld922 View Post
    What are the expected outputs, and what outputs are you actually getting?
    The code is supposed to input a start an end and an interval which the program does fine... the problem is in the if(a != 'y' || a != 'Y' || a != 'n' || a != 'N') it enters the body even IF character a is equal to one of the four variables

  6. #6
    Super Moderator Norm's Avatar
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    Default Re: Whats wrong with my looping?

    What do you see when you add this print statement to the code just before the while() test?
    System.out.println("cond=" + (a != 'y' || a != 'Y' || a != 'n' || a != 'N') + " for a=" + a);

  7. The Following User Says Thank You to Norm For This Useful Post:

    argie123sky (August 21st, 2010)

  8. #7
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    Default Re: Whats wrong with my looping?

    Quote Originally Posted by Norm View Post
    What do you see when you add this print statement to the code just before the while() test?
    System.out.println("cond=" + (a != 'y' || a != 'Y' || a != 'n' || a != 'N') + " for a=" + a);
    that helped ty

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