<?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.111cn.net  绿色软件
$str = '<p><img title="绿色软件" alt="绿色软件" onload="ResizeImage(this,860)" src="http://www.111cn.net /data/soft_img/2010091101619.jpg" /></p><p><img title="绿色软件" alt="绿色软件" onload="ResizeImage(this,860)" src="http://www.111cn.net /data/soft_img/2010091029938.jpg" /></p><p><img title="绿色软件" alt="绿色软件" onload="ResizeImage(this,860)" src="http://www.111cn.net /data/soft_img/2010092839019.jpg" /></p>';
preg_match_all("/(href|src)=(["|']?)([^ "'>]+.($ext))\2/i", $str, $matches);
var_dump($matches);
?>

array(5) {
  [0]=>
  array(3) {
    [0]=>
    string(57) "src="http://www.111cn.net /data/soft_img/2010091101619.jpg""
    [1]=>
    string(57) "src="http://www.hzhuti.com/sonyericsson/w715/ 2010091029938.jpg""
    [2]=>
    string(57) "src="http://www.111cn.net /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.111cn.net /data/soft_img/2010091101619.jpg"
    [1]=>
    string(51) "http://www.111cn.net /data/soft_img/2010091029938.jpg"
    [2]=>
    string(51) "http://www.111cn.net /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);