package co.spillikin.java.jkia;
/**
 * The clever way to reverse a string, while taking up no 
 * additional memory.
 * @author chris
 */
public class ReverseAString {

	/**
	 * If this were a C String, an alternative would be to swap thru
	 * the zero terminator.
	 * However the most clever way to reverse a string without using 
	 * any additional memory is to use XOR, and this works for any 
	 * type of string.
	 * @param args
	 */
	public static void main(String[] args) {
		// Test a string with an even number of characters.
		// char data[] = {'a', 'b', 'c', 'd'};
		// Test a string with an odd number of characters.
		char data[] = {'a', 'b', 'c', 'd', 'e'};
		// Dividing an int will of course truncate down for odd lengths.
		// We don't need to reverse a middle char in that case.
		System.out.println("Initial string " + new String(data));
		int	strlength = data.length;
		for ( int i = 0; i < strlength / 2; i++) {
			data[i] = (char) (data[i] ^ data[strlength - i - 1]);
			data[strlength - i - 1] = (char) (data[i] ^ data[strlength - i - 1]);
			data[i] = (char) (data[i] ^ data[strlength - i - 1]);
		}
		System.out.println("Final string " + new String(data));
	}

}