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5 Digit palindrome array problem

 
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5 Digit palindrome array problem
JayCom1969
16 Jun, 2008 - 11:26 AM
Post #1

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After looking through the forum I wasn't able to find anyone that has had the issue that I'm having.

I need to write a program to initialize an array of size 25, and then place a palindrome in each spot. After that I need to determine whether they are even or odd, and give the totals of each.

My thought process was to get a random 5 digit number, then determine the digits in it. After that I had the program look at digit 1 and digit 5, and if they weren't equal to each other then have it go back to the part where it generated a random number again.

The program compiles fine, but when I run it all I get for an output is a couple of palindromes and a bunch of zeros.

I think my problem is in the area where I do the digits not being equal to each other... I though that if I had an if statement to do the comparison (not equal to each other) followed by a continue that it would go back to the top of the loop. It just doesn't seem to be doing that.

If the number generated isn't a palindrome it looks to me that it just continues, but it does work when the randomly generated number is a palindrome the first time.

Thanks for any help, my code follows.

Jay

CODE

class Mod7Prob1

{

    public static void main(String args[])

    {

        // Declaring variables

        int digit1, digit2, digit3, digit4, digit5;

        int even, odd;

        int number, i, n;

        int pals[];

        pals = new int[25];

        i = 0;

        even = 0;

        odd = 0;

                        

        // While loop to get palindromes

        while (i<25)

        {

            // Getting random 5 digit number

            n = 0;

            n = (int)Math.floor(Math.random()*100000+1);

                        

            // Determining digits in number

            number = n;

            digit1 = n%10;

            n = n/10;

            digit2 = n%10;

            n = n/10;

            digit3 = n%10;

            n = n/10;

            digit4 = n%10;

            digit5 = n/10;

            

            // Using if logic to determine palindrome

            if (digit1 != digit5) continue;

            if (digit1 == digit5)

            {

                if (digit2 == digit4)

                    {

                        pals [i] = number;

                        if (number%2 == 0)

                        {

                            even++;

                        }

                        else

                        {

                            odd++;

                        }

                    }

            }

            

            i++;

        }

        System.out.println("Palindromes are: ");

        for (i=0; i<25; i++)

        {

            System.out.print(pals[i]+" ");

        }

        System.out.println("");

        System.out.println("Number of even palindromes "+even);

        System.out.println("Number of odd palindromes "+odd);

    }

}


This post has been edited by JayCom1969: 16 Jun, 2008 - 01:01 PM
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nick2price
RE: 5 Digit Palindrome Array Problem
16 Jun, 2008 - 11:45 AM
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Heres a good example you could just modify to suit your needs. What it basically does is reverse the number then checks it against the original number.
CODE
public class Palindrome  {
      public static void main(String [] args){
      try{
      BufferedReader object = new BufferedReader(
                  new InputStreamReader(System.in));
      System.out.println("Enter number");
      int num= Integer.parseInt(object.readLine());
        int n = num;
        int rev=0;
        System.out.println("Number: ");
        System.out.println(" "+ num);
        for (int i=0; i<=num; i++){
          int r=num%10;
          num=num/10;
          rev=rev*10+r;
          i=0;
        }
        System.out.println("After reversing the number: "+ " ");
        System.out.println(" "+ rev);      
        if(n == rev){
        System.out.print("Number is palindrome!");
        }
        else{
        System.out.println("Number is not palindrome!");
        }
      }
      catch(Exception e){
        System.out.println("Out of range!");
      }
  }
}  


This post has been edited by nick2price: 16 Jun, 2008 - 11:47 AM
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JayCom1969
RE: 5 Digit Palindrome Array Problem
16 Jun, 2008 - 01:26 PM
Post #3

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Joined: 16 Jun, 2008
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I figured it out... I had the program go back to the top of the while loop if digit1 did not equal digit5, but I didn't address what to do if digit4 didn't equal digit2.

I threw in an "else continue" statement in line with digit2 being equal to digit4 and it runs like a charm... I just needed to walk away and have a beer for it to make sense!

So here's what I ended up with. Pretty clunky, but it works...

CODE

class Mod7Prob1

{

    public static void main(String args[])

    {

        // Declaring variables

        int digit1, digit2, digit3, digit4, digit5;

        int even, odd;

        int number, i, n;

        int pals[];

        pals = new int[25];

        i = 0;

        even = 0;

        odd = 0;

                        

        // While loop to get palindromes

        while (i<25)

        {

            // Getting random 5 digit number

            n = 0;

            n = (int)Math.floor(10000+Math.random()*(99999-10000+1));

                        

            // Determining digits in number

            number = n;

            digit1 = n%10;

            n = n/10;

            digit2 = n%10;

            n = n/10;

            digit3 = n%10;

            n = n/10;

            digit4 = n%10;

            digit5 = n/10;

            

            // Using if logic to determine palindrome

            if (digit1 != digit5) continue;

            if (digit1 == digit5)

            {

                if (digit2 == digit4)

                    {

                        pals [i] = number;

                        if (number%2 == 0)

                        {

                            even++;

                        }

                        else

                        {

                            odd++;

                        }

                    }

                else continue;

            }

            

            i++;

        }

        System.out.println("Palindromes are: ");

        for (i=0; i<25; i++)

        {

            System.out.println(pals[i]+" ");

        }

        System.out.println("");

        System.out.println("Number of even palindromes "+even);

        System.out.println("Number of odd palindromes "+odd);

    }

}
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