<?php
$base = ‘ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789‘;
$words = 5;
$rand_top = strlen($base) - 1;
$string = ‘‘;
header("Content-type: image/png");
$im = imagecreate($words*16, $words*5);
$black = imagecolorallocate($im, 90, 60, 120);
$white = imagecolorallocate($im, 255, 255, 255);
for($i=0;$i<$words;$i++){
$idx = mt_rand(0, $rand_top);
imagestring($im, 3, $i*15+2, mt_rand(0, $words*2), $base[$idx], $white);
}
imagepng($im);
imagedestroy($im);
?>產生圖片隨機字串
原文：http://www.jb51.net/article/5121.htm
