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Thread: Help With Three Part Program

  1. #1
    Junior Member
    Join Date
    Sep 2012
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    Default Help With Three Part Program

    Ok, so I have to write a program that takes a low and high number and an input filename from the command line and has to do the following three things:

    1) Print all primes numbers in the range from low to high on a single line, separated by a space.
    2) Print all perfect numbers in the range from low to high on a single line, separated by a space.
    3) Echo the words from the input file and indicate if they are palindromes or not.

    My code is as follows:

    port java.io.*;
    import java.util.*;

    public class Program3

    public static void main (String[] args)

    int lo=0,hi=0; // range of #s to look for primes and perfects
    String infileName; // file of Strings, one per line
    BufferedReader infile = null;

    if (args.length < 3)
    System.out.println("CMD LINE INPUT ERROR: Must enter 2 numbers followed by name of input file on cmd line.");


    for(int n=lo; n<=hi; n++){
    boolean isPrime = (n%2 != 0);
    int divisor=3;

    while(isPrime && divisor<n/2);

    if (isPrime)
    System.out.print(n + " ");

    for (int perfectNum=lo; perfectNum<=hi; perfectNum++)
    int total=0;
    for (int perfectDiv=1 ; perfectDiv<perfectNum;perfectDiv++)
    if (perfectNum % perfectDiv==0) total=total+perfectDiv;
    if (perfectNum==total) System.out.print(perfectNum + " ");

    String line=null;
    BufferedReader bufferedReader = new BufferedReader(new FileReader(infileName));
    while (infile.ready())
    line = infile.readLine();
    boolean isPalindrome=true;

    int lineLength = line.length();
    int middleOfline = lineLength/2;

    for (int beginningLetter = 0; beginningLetter<middleOfline; beginningLetter++ )
    if (line.charAt(beginningLetter) != line.charAt(lineLength-beginningLetter-1))
    if (isPalindrome)
    System.out.println( line + " IS a palindrome." );
    System.out.println( line + " NOT a palindrome." );



    catch ( Exception e)
    StringWriter sw = new StringWriter();
    e.printStackTrace(new PrintWriter(sw));
    System.out.println("EXCEPTION CAUGHT: " + sw.toString() );
    System.exit( 0 );

    I'm getting a few problems. First of all, whenever I input any number greater than 7, my terminal only displays 1, 3, 5, and 7, but no other primes. My perfect number section is printing 6 and 28 multiple times instead of one on the same line, separated by a space. Finally, I'm not sure that my BufferedReader syntax is correct, and each time I attempt to execute the problem, it says that the file I am trying to read does not exist.

    Any help or suggestions would be greatly appreciated!


  2. #2
    Super Moderator Norm's Avatar
    Join Date
    May 2010
    Eastern Florida
    Thanked 2,274 Times in 2,245 Posts

    Default Re: Help With Three Part Program

    Can you copy and paste here the full contents of the console window from when you execute the program that shows the input to the program and its output?

    On windows: To copy the contents of the command prompt window:
    Click on Icon in upper left corner
    Select Edit
    Select 'Select All' - The selection will show
    Click in upper left again
    Select Edit and click 'Copy'

    Paste here.

    Please Edit your post and wrap your code with
    to get highlighting and preserve formatting.
    Last edited by Norm; September 27th, 2012 at 04:36 PM.
    If you don't understand my answer, don't ignore it, ask a question.

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