/* Naomi Tilsen
  CS 111A
  Programming Lab 5 (programmingLab4.java)
  Apply for extra credit.
  "Palindrome Detector" is a program to take a string or sentence input from the
  user on the console, and check it to see if it is a palindrome. The program uses
  arrays and two user-defined methods to accomplish the task. This program will not
  recognize numbers as part of a valid palindrome.
*/

import java.util.Scanner;

class ProgrammingLab5
{
  // class level variables: best to avoid them, but here are two:
  static int countLettersArray = 0; // the number of letters in array. Set by "removesNonLetters"
  static String getString; // the string input by the user. Turned into an array,
                           // but saved as string for output.

  public static void main(String[] args)
  {
     int numLoops;
     boolean lettersMatch = false;

     char[] arrayIn = getArray();
                  // call function getArray to get user input and save returned array as arrayIn
     char[] lettersArray = removesNonLetters(arrayIn);
                                   // call function removesNonLetters to make sure that all
                                   // elements of the array are lower case letters

     if (countLettersArray % 2 == 1)
                        // if there are an odd number of letters
        numLoops = (countLettersArray - 1)/2;
                   // initialize the maximum number of loops to reflect the odd routine
     else
        numLoops = countLettersArray/2;
                   // initialize the maximum number of loops to reflect the even routine

     for ( int counter = 0; counter < numLoops; counter ++)
     {

        if ( lettersArray[counter] == lettersArray[countLettersArray - (counter +1)] )
                        // compare the first element of the array with the last, etc.
        {
           lettersMatch = true;
        }
        else
        {
           lettersMatch = false;
        break;
        }

     }                 // end for loop to check for matching letters

     if (lettersMatch)
        System.out.println ("The word/sentence you entered, '" +getString +"' is a palindrome.");
     else
        System.out.println ("The word/sentence you entered, '" +getString +"' is not a palindrome.");


  }             // end method main


  /* User-defined method getArray uses Scanner to take a string from the
     user via the console, and saves each entry as an element of an array.
     The array is then returned to the calling method as arrayIn.
  */
  static char[] getArray ( )
  {
     Scanner keyIn = new Scanner (System.in);

     System.out.println( "Welcome to the Palindrome Detector. Please enter a palindrome." );
     System.out.print( "You may enter a word or a sentence - numbers and punctuation don't count. \n> ");

     getString = keyIn.nextLine();  // save keyIn input line as getString

     char getElements[] = getString.toCharArray();
                         // save getString as as new char array getElements

     return getElements;
  }              // end method getArray


  /* User-defind method removesNonLetters accepts an array of String elements
     checks to see which elements are not letters, and saves the letters only
     to a second array without spaces or non-letter characters. The second array
     is then returned to the calling method as lettersArray.
  */

  static char[] removesNonLetters ( char arrayIn[] )
  {
     countLettersArray = 0;
     char[] lettersArray = new char [arrayIn.length];
                           // assume the length of the new array will be
                           // equal to or less than the length of arrayIn

     for ( int countArrayIn = 0; countArrayIn <= arrayIn.length - 1; countArrayIn ++)
     {
        if ( Character.isLetter(arrayIn[countArrayIn]) )   // if element in arrayIn is a letter
        {
           lettersArray[countLettersArray] = Character.toLowerCase(arrayIn[countArrayIn]);
                                               // convert that element to lower case and copy it
                                              // into the next index for lettersArray
           countLettersArray ++;  // use this number to count the number of loops in main method
        }
     }               // end for loop to convert arrayIn to lettersArray

     return lettersArray;

  }               // end method removesNonLetters

}                // end class ProgrammingLab5


/********* Begin output for ProgrammingLab4.java *********

C:\j2sdk1.4.2_03\docs>javac ProgrammingLab4.java

C:\j2sdk1.4.2_03\docs>java ProgrammingLab4
Welcome to the Palindrome Detector. Please enter a palindrome.
You may enter a word or a sentence - numbers and punctuation don't count.
> radar
The word/sentence you entered, 'radar' is a palindrome.

C:\j2sdk1.4.2_03\docs>java ProgrammingLab4
Welcome to the Palindrome Detector. Please enter a palindrome.
You may enter a word or a sentence - numbers and punctuation don't count.
> A man, a plan: a canal - Panama!
The word/sentence you entered, 'A man, a plan: a canal - Panama!' is a palindrome.

C:\j2sdk1.4.2_03\docs>java ProgrammingLab4
Welcome to the Palindrome Detector. Please enter a palindrome.
You may enter a word or a sentence - numbers and punctuation don't count.
> abcdeedcba
The word/sentence you entered, 'abcdeedcba' is a palindrome.

C:\j2sdk1.4.2_03\docs>java ProgrammingLab4
Welcome to the Palindrome Detector. Please enter a palindrome.
You may enter a word or a sentence - numbers and punctuation don't count.
> abcdecba
The word/sentence you entered, 'abcdecba' is not a palindrome.

C:\j2sdk1.4.2_03\docs>java ProgrammingLab4
Welcome to the Palindrome Detector. Please enter a palindrome.
You may enter a word or a sentence - numbers and punctuation don't count.
> Good Dog!
The word/sentence you entered, 'Good Dog!' is not a palindrome.

C:\j2sdk1.4.2_03\docs>
********* End output for ProgrammingLab4.java *********/