匹配内容中的图片怎么写正则表达式

Question

内容代码：
[{"url":"http:\/\/127.0.0.201\/uploadfile\/2017\/1025\/20171025041011234.jpg","alt":"1"},{"url":"http:\/\/127.0.0.201\/uploadfile\/2017\/1025\/20171025041020836.jpg","alt":"2"},{"url":"http:\/\/127.0.0.201\/uploadfile\/2017\/1025\/20171025041027314.jpg","alt":"3"}]匹配代码：
if(preg_match_all("/(=>)\s([\b\"|']?)([^ \"'>]+\.(gif|jpg|jpeg|bmp|png))\\2/i", $pictureurls, $matches)) {
$systeminfo['thumb'] = $matches[3][$auto_thumb_no];这段代码不行，请问应该怎么写

Answer 1

$pictureurls = '[{"url":"http:\/\/127.0.0.201\/uploadfile\/2017\/1025\/20171025041011234.jpg","alt":"1"},{"url":"http:\/\/127.0.0.201\/uploadfile\/2017\/1025\/20171025041020836.jpg","alt":"2"},{"url":"http:\/\/127.0.0.201\/uploadfile\/2017\/1025\/20171025041027314.jpg","alt":"3"}]';
$json = json_decode($pictureurls);foreach ($json as $img){
     foreach ($img as $key => $value){
         echo $key . ':' . $value . '<br/>';
         }
    }
preg_match_all('/http.+?(gif|jpg|jpeg|bmp|png)/',$pictureurls,$arr);
echo '<pre>';
var_dump($arr[0]);
echo '</pre>';

Answer 2

$s = '[{"url":"http:\/\/127.0.0.201\/uploadfile\/2017\/1025\/20171025041011234.jpg","alt":"1"},{"url":"http:\/\/127.0.0.201\/uploadfile\/2017\/1025\/20171025041020836.jpg","alt":"2"},{"url":"http:\/\/127.0.0.201\/uploadfile\/2017\/1025\/20171025041027314.jpg","alt":"3"}]';
print_r(json_decode($s, true));
Array
(
    [0] => Array
        (
            [url] => http://127.0.0.201/uploadfile/2017/1025/20171025041011234.jpg
            [alt] => 1
        )    [1] => Array
        (
            [url] => http://127.0.0.201/uploadfile/2017/1025/20171025041020836.jpg
            [alt] => 2
        )    [2] => Array
        (
            [url] => http://127.0.0.201/uploadfile/2017/1025/20171025041027314.jpg
            [alt] => 3
        ))