Dump a string in a hexidecimal representation similar to terminal based hex-editors.

hex_dump.php

<?php
/*
* hex_dump.php
*
* Copyright 2011 mot <@fsfe.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/

/**
 * dump a string in hex notation
 * next to the string data.
 * 
 * nonprintable characters are displayed
 * as .
 * 
 * 16 characters per line, as an 8-char
 * pair. Hexadecimal and decimal off-
 * set values on each line.
 */
function hex_dump($string)
{
    $len=strlen($string);
    $rows=$len/16;
    for($r=0; $r<$rows; $r++)
    {
        $offset=$r*16;
        $hex = '';
        $text = '';
        for($i=0;$i<16&&$offset+$i<$len;$i++)
        {
            $pos = $offset+$i;
            $char = $string[$pos];
            $text .= ctype_print($char) ? $char : '.';
            $hex .= sprintf('%02X ', ord($char));
            if ($i==7)
            {
                $text.='  ';  $hex.=' ';
            }
        }
        printf("%02X %03d  %-50s  %s\n", $offset, $offset, rtrim($hex), $text);
    }
}