// APS101, Winter 2009: Lecture 20 (Mar. 2)
//
// Monitor the A2 FAQ page for announcements about TA office hours this week
// (most likely Wed. 2-3pm, in BA4177, and next Mon. 12-2pm)
//
// Tomorrow's tutorial is IMPORTANT - will help you with A2:
// - binary representation
// - exclusive-or
// - the encryption algorithm
// - other hints 
//
// Note about converting char values to ASCII: it's easy.

char x = 'a'
(int) x
int x = 'a' // this works as well

// Review: last time we wrote the HighLow game
// it wasn't user-friendly enough, so we wrote a
// Graphical User Interface (GUI) for it.
// Then, we added a while loop. 

HighLowGUI2 h = new HighLowGUI2(10)
h.makeGuess() // need to do this only once now!

// exercise: modify the code so that there is a limit on how many
             guesses a player gets.

// what if we want to print the squares of numbers from 1 to 4:
System.out.println(1 * 1);
System.out.println(2 * 2);
System.out.println(3 * 3);
System.out.println(4 * 4);

// what if we want to do it for 1 to 300?
// we need a loop!

WhileDemo.printSquares(10)

// how about printing a String backwards:
WhileDemo.printRString("ABCD")

String s = WhileDemo.printRString("ABCD");  // what's  wrong? how do we store the result?

// we need to write a method that reverses the String and returns the result as a String.
// reversing a String:  "abcd" -> "dcba"
// starting from the end, we go backwards and concatenate characters:
//  "d" 
//       + "c"
//
//	        + "b"
//                    + "a"
// end index: length - 1
// character at position i: s.charAt(i)

WhileDemo.reverseString("ABCD")

String s = WhileDemo.reverseString("ABCD")

// let's do it another way (there are many different ways to do it)

WhileDemo.reverseString2("ABCD")

// for loops:

for (initialization; condition; update statement) {
   body;
}

* for loops are good to use when you know the range *

// now, let's do the String reversal using a for loop.
ForDemo.reverse("ABCD")

(take a look at the tester for reverse in ForDemo - TesterFor.java.
we didn't cover this in lecture, but it's very simple!)

// palindromes: ex. "wow", "lol", "racecar"
// let's write a method that checks whether a String is a palindrome by
// testing whether the given String is equal to its reverse.
WhileDemo.isPalindrome("racecar") // true
WhileDemo.isPalindrome("haha") // false

WhileDemo.isPalindrome("") // also true... we want it to be false

WhileDemo.isPalindrome("Racecar") // false... we want this to be true
// use String method toLowerCase() to fix this

WhileDemo.isPalindrome("Racecar ") // false, because of the extra space at the end
// use the trim() method to get rid of preceding and trailing whitespace

* also, take a look at methods countChars and mystery in WhileDemo - we'll go over them tomorrow *