/*  This program converts an input number from hexadecimal (base 16) to decimal (base 10)
 *	To perform this conversion, convert each digit from 0-9,A-F into 0-15 and add it to
 *  the previous value * 16.  For instance, if the input is 123, then 1 converts to 1, 
 *  multiply by 16 and add to 2 (18), multiply by 16 and add to 3 = 291. */

import java.util.Scanner;

public class Hex2Dec
{
	public static void main(String[] args)
	{
		Scanner in = new Scanner(System.in);
		System.out.print("Enter a hexadecimal number  ");
		String value = in.next();								// get the hex value as a String
		char temp;												// used to store each digit,one at a time
		int number = 0, temp2 = 0;								// number is the converted number (so far)
		for(int i=0;i<value.length();i++)						// temp2 is the current hex digit converted to decimal
		{		// iterate for each character in value
			temp = value.toUpperCase().charAt(i);				// grab the character, lower case it
			switch(temp) {										// map it to the appropriate decimal value
				case '0' : temp2 = 0;break;
				case '1' : temp2 = 1;break;
				case '2' : temp2 = 2;break;
				case '3' : temp2 = 3;break;
				case '4' : temp2 = 4;break;
				case '5' : temp2 = 5;break;
				case '6' : temp2 = 6;break;
				case '7' : temp2 = 7;break;
				case '8' : temp2 = 8;break;
				case '9' : temp2 = 9;break;
				case 'A' : temp2 = 10;break;
				case 'B' : temp2 = 11;break;
				case 'C' : temp2 = 12;break;
				case 'D' : temp2 = 13;break;
				case 'E' : temp2 = 14;break;
				case 'F' : temp2 = 15;break;
				default: System.out.println("Error, the character " + temp2 + " is not a legal hexadecimal digit, trying to continue...");
			}
			number = number * 16 + temp2;						// add the new digit to our number
		}
		System.out.println("The hexadecimal value " + value + " is equal to " + number + " in decimal");
	}
}