php生成密保卡

<?php
/**
* Author:       wonli
* Contact:      wonli@live.com
* Date:         2011-09
* Description:  getvcode()
*/
$st = microtime(true);
function getvcode()
{
    $s = array();
    $str = '3456789abcdefghjkmnpqrstuvwxy';
    for($k = 65; $k<74; $k++)
    {
        for($i = 1; $i<=9; $i++)
        {
            $_x=substr(str_shuffle($str), $i, $i+2);
            $s[chr($k)][$i] = $_x[0].$_x[1];
        }
    }
    return $s;
}
$s = getvcode();
$b = serialize($s);
echo '<style type="text/css">table{width:350px;height:350px;border:1px solid blue;margin:20px;border-collapse: collapse; }td{text-align:center;border:1px solid #dddddd;} .b{background:#ffffee;} .c{background:#eeffff;}</style>';
echo '<table><tr><td>  </td>';
for($i=1;$i<=9;$i++)
{
    echo '<td class="b">'.$i.'</td>';
}
echo '</tr>';
foreach($s as $k=>$v)
{
    echo '<tr><td class="c">'.$k.'</td>';
    for($i=1;$i<=9;$i++)
    {
        echo '<td>'.$v[$i].'</td>';
    }
    echo '</tr>';
}
echo '</table>';
echo '<p style="margin-top:20px"></p>';
$et = microtime(true);
echo round(($et - $st) * 1000, 2).' 毫秒',' <a href="?view">查看</a> ',' <a href="?close">关闭</a>';
if(isset($_GET['view']))
{
    echo '<p style="margin-top:100px;"><textarea name="" id="" cols="130" rows="10">'.$b.'</textarea></p>';
} elseif(isset($_GET['close'])) {
}

function getvcode()
{
    $s = array();
    $str = '3456789abcdefghjkmnpqrstuvwxy';

    for($k = 65; $k<74; $k++)
    {
        for($i = 1; $i<=9; $i++)
        {
            $_x=substr(str_shuffle($str), $i, $i+2);
            $s[chr($k)][$i] = $_x[0].$_x[1];
        }
    }
    return $s;
}