/*
 * Problem 2, Lab 10, Wednesday 29th October
 * Write recursive method printIntInNewBase to print an integer in any base from 2 through 
 * hexadecimal (base 16) without using an array. Input must be assumed to be in base 10
 * from command line. Use characters ’A’, ’B’, ’C’, ’D’, ’E’, ’F’ for 10, 11, 12, 13, 14, 15
 * respectively. For example, 512 in base 16 is 200, and 511 in base 16 is 1FF 
 */

public class BaseConversion {

	public static void main(String args[]) {
		if (args.length != 2) {
			System.out.println("Invalid Command line arguements.");
			return;
		}
		int num, base;
		try {
			num = Integer.parseInt(args[0]);
			base = Integer.parseInt(args[1]);
		} catch (NumberFormatException ex) {
			System.out.println("Invalid Command line arguements.");
			return;
		}
		if(base < 2 || base > 16) {
			System.out.println("Invalid Command line arguement :: base " + base);
			return;
		}
		if(num < 0) {
			System.out.println("Invalid Command line arguement :: num " + base);
			System.out.println("Positive num required");
			return;
		}
		System.out.print(num + " in base " + base + " is ");
		printInNewBase(num,base);
	}

	private static void printInNewBase(int num, int base) {
		if(num == 0) 
			return;
		
		printInNewBase(num/base, base);
		int remainder = num%base;
		switch (remainder) {
			case 0:
			case 1:
			case 2:
			case 3:
			case 4:
			case 5:
			case 6:
			case 7:
			case 8:
			case 9:
				System.out.print(remainder);
				break;
			case 10:
				System.out.print('A');
				break;
			case 11:
				System.out.print('B');
				break;
			case 12:
				System.out.print('C');
				break;
			case 13:
				System.out.print('D');
				break;
			case 14:
				System.out.print('E');
				break;
			case 15:
				System.out.print('F');
				break;
				
		}
		
	}

}