PHP提取HTML代码中img标签下src属性

需求：提取整片文章中img的src属性，并保存到一个数组当中

preg_match_all("/(href|src)=(["|']?)([^"'>]+.(jpg|JPG|jpeg|JPEG|gif|GIF|png|PNG))/i", $content,$out,PREG_PATTERN_ORDER);

测试数据

<p>
<img src="/Shop/Upload/ueditor/20171221/1513806081642421.jpg" title="1513806081642421.jpg" alt="Desert.jpg"/></p><p>
<img src="/Shop/Upload/ueditor/20171221/1513806089468745.jpg" title="1513806089468745.jpg" alt="Chrysanthemum.jpg"/>&nbsp;</p>

结果

array (size=5)
  0 => 
    array (size=2)
      0 => string 'src="/Shop/Upload/ueditor/20171221/1513806081642421.jpg' (length=55)
      1 => string 'src="/Shop/Upload/ueditor/20171221/1513806089468745.jpg' (length=55)
  1 => 
    array (size=2)
      0 => string 'src' (length=3)
      1 => string 'src' (length=3)
  2 => 
    array (size=2)
      0 => string '"' (length=1)
      1 => string '"' (length=1)
  3 => 
    array (size=2)
      0 => string '/Shop/Upload/ueditor/20171221/1513806081642421.jpg' (length=50)
      1 => string '/Shop/Upload/ueditor/20171221/1513806089468745.jpg' (length=50)
  4 => 
    array (size=2)
      0 => string 'jpg' (length=3)
      1 => string 'jpg' (length=3)