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Thread: need help with loops plz

  1. #1
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    Default need help with loops plz

    hi i am new to java programming and im working on a looping program involving the fibonacci numbers.
    what i would like to do is to have a program that asks the user how many values of the Fibonacci sequence to output. Then i want to create a loop that outputs the number of values of the Fibonacci sequence requested by the user.
    i only want to use the do....while loop, for loop, and the while loop
    the following code i will post does not do what i want and i cannot figure out why
    first off when i input a number it doesnt display the desired out......it just displays the same exact 15 numbers
    and second my for loop works but all the other ones do not
    any help would be very much appreciated ty

    import javax.swing.JOptionPane;
     
    public class Lab4
    {
      public static void main(String[] args)
      {
        String aString="15";
        String userInput = JOptionPane.showInputDialog("How many values of the Fibonacci sequence would you like?");
        int aInt = Integer.parseInt(aString);
        for1();
        do1();
        while1();
        for2();
        do2();
        while2();
      }
     public static void for1()
     {
        String aString="15";
        String userInput = JOptionPane.showInputDialog("How many values of the Fibonacci sequence would you like?");
        int aInt = Integer.parseInt(aString);
        for(int i = 1; i <= aInt; i++)
        {
          int f = fib(i);
          System.out.println("Fib(" + i + ") = " + f);
        }
      }
     
     
     public static void do1()
     {
        String bString="15";
        String userInput = JOptionPane.showInputDialog("How many values of the Fibonacci sequence would you like?");
        int bInt = Integer.parseInt(bString);
       do
       {
         int f = fib(i);
       }
       while(int h = 1; h <= bInt; h++);
       System.out.println("Fib(" + h + ") = " + f);
     }
     
     public static void while1()
     {
        String cString="15";
        String userInput = JOptionPane.showInputDialog("How many values of the Fibonacci sequence would you like?");
        int cInt = Integer.parseInt(cString);
        while(int i = 1; i <= cInt; i++)
        {
          int f = fib (i);
          System.out.println("Fib(" + i + ") = " + f);
        }
     
     
      public static int fib(int n)
        { 
           if (n <= 2)
                return 1;
           else
                return fib(n - 1) + fib(n - 2);
        }
    }
    Last edited by JavaPF; September 23rd, 2009 at 04:16 PM. Reason: Please use [code] ... [/code] tags


  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: need help with loops plz

    public static void main(String[] args)
    {
         Scanner input = new Scanner(System.in);
         System.out.println("Input number of fib numbers to finds: ");
         int end = input.nextInt();
         System.out.println("1\n1");
         int fib1 = 1;
         int fib2 = 1;
         for(int i = 3; i < end; i++)
         {
              int temp = fib1+fib2;
              System.out.println(temp);
              fib1 = fib2;
              fib2 = temp;
         }
    }

  3. #3
    Java kindergarten chronoz13's Avatar
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    Default Re: need help with loops plz

    i've red a book exercise and it describes fibonacci , ( a pare of rabbit that matures in 2 months and capabale of reproducing every after maturity), is that exactly what fibonacci system is?

  4. #4
    Super Moderator helloworld922's Avatar
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    Default Re: need help with loops plz

    mm... rabbits don't normally reproduce via the fibonacci sequence. Instead, they reproduce exponentially (actually, to be more precise the produce logarithmically, at some point their population will be limited by some factors). Neither of these follows the fibonacci sequence.

    The fibonacci sequence is this:

    Start with 1 and 1.

    Add the terms: 1+1 = 2 is the next term.

    Keep adding the 2 previous terms for the next term.

    1+2=3
    2+3=5
    3+5=8
    ....

    In fact, the fibonacci grows at a much faster rate than most functions (even exponentials). I think the one exponential that does grow faster than fibonacci is x^x (don't take my word for it, though). I'm not sure if fibonacci grows faster than factorials, either.
    Last edited by helloworld922; September 23rd, 2009 at 07:40 PM.

  5. #5
    Java kindergarten chronoz13's Avatar
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    Default Re: need help with loops plz

    i didnt post the exact details.. here it is..


    "suppose we have a pair of rabbits (assuming that these rabbits dont die) a pair of rabbits will mature in 2 months. and they are capable of reproducing another pair after maturity(after 2 months)

    is this a fibonacci sequence?

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