<?php
//取得页面所有的图片地址
function getimages($str)
{
$match_str = "/((http://)+([^ rn()^$!`"'|[]{}<>]*)((.gif)|(.jpg)|(.bmp)|(.png)|(.GIF)|(.JPG)|(.PNG)|(.BMP)))/";
preg_match_all ($match_str,$str,$out,PREG_PATTERN_ORDER);
return $out;
}
?> 

preg_match_all("/<img.*srcs*=s*["|']?s*([^>"'s]*)/i",str_ireplace("\","",$content),$arr); 

<?php
$ext = 'gif|jpg|jpeg|bmp|png';//罗列图片后缀从而实现多扩展名匹配 by http://www.1sucai.cn 绿色软件
$str = '<p><img title="绿色软件" alt="绿色软件" onload="ResizeImage(this,860)" src="http://www.1sucai.cn /data/soft_img/2010091101619.jpg" /></p><p><img title="绿色软件" alt="绿色软件" onload="ResizeImage(this,860)" src="http://www.1sucai.cn /data/soft_img/2010091029938.jpg" /></p><p><img title="绿色软件" alt="绿色软件" onload="ResizeImage(this,860)" src="http://www.1sucai.cn /data/soft_img/2010092839019.jpg" /></p>';
preg_match_all("/(href|src)=(["|']?)([^ "'>]+.($ext))\2/i", $str, $matches);
var_dump($matches);
?> 

array(5) {
[0]=>
array(3) {
[0]=>
string(57) "src="http://www.1sucai.cn /data/soft_img/2010091101619.jpg""
[1]=>
string(57) "src="http://www.hzhuti.com/sonyericsson/w715/ 2010091029938.jpg""
[2]=>
string(57) "src="http://www.1sucai.cn /data/soft_img/2010092839019.jpg""
}
[1]=>
array(3) {
[0]=>
string(3) "src"
[1]=>
string(3) "src"
[2]=>
string(3) "src"
}
[2]=>
array(3) {
[0]=>
string(1) """
[1]=>
string(1) """
[2]=>
string(1) """
}
[3]=>
array(3) {
[0]=>
string(51) "http://www.1sucai.cn /data/soft_img/2010091101619.jpg"
[1]=>
string(51) "http://www.1sucai.cn /data/soft_img/2010091029938.jpg"
[2]=>
string(51) "http://www.1sucai.cn /data/soft_img/2010092839019.jpg"
}
[4]=>
array(3) {
[0]=>
string(3) "jpg"
[1]=>
string(3) "jpg"
[2]=>
string(3) "jpg"
}
}

$newstext=preg_replace(preg_replace('/(<img[^>]+srcs*=s*”?([^>"s]+)”?[^>]*>)/im', ‘<a href=”$2″>$1</a>', $newstext);