Below is the syntax highlighted version of Hex2Decimal.java
from §3.1 Using Data Types.
/****************************************************************************** * Compilation: javac Hex2Decimal.java * Execution: java Hex2Decimal x * * Functions to convert x from hex to decimal and back. * * % java Hex2Decimal 1F * 31 * * % java Hex2Decimal FF * 255 * * % java Hex2Decimal DEAD * 57005 * * Alternate solution: Integer.parseInt(s, 16) * This is more robust and works with negative integers. * ******************************************************************************/ public class Hex2Decimal { public static int hex2Decimal(String s) { String digits = "0123456789ABCDEF"; s = s.toUpperCase(); int val = 0; for (int i = 0; i < s.length(); i++) { char c = s.charAt(i); int d = digits.indexOf(c); val = 16*val + d; } return val; } // precondition: d is a nonnegative integer public static String decimal2Hex(int d) { String digits = "0123456789ABCDEF"; if (d == 0) return "0"; String hex = ""; while (d > 0) { int digit = d % 16; // rightmost digit hex = digits.charAt(digit) + hex; // string concatenation d = d / 16; } return hex; } public static void main(String[] args) { int decimal = hex2Decimal(args[0]); StdOut.println(decimal); String hex = decimal2Hex(decimal); StdOut.println(hex); } }