/* PHP正则提取图片img标记中的任意属性 */
$str = '<center><img src="https://www.jb51.net/uploads/images/20100516000.jpg"><br />PHP正则提取或更改图片img标记中的任意属性</center>';
//1、取整个图片代码
preg_match('/<\s*img\s+[^>]*?src\s*=\s*(\'|\")(.*?)\\1[^>]*?\/?\s*>/i',$str,$match);
echo $match[0];
//2、取width属性
preg_match('/<img.+(width=\"?\d*\"?).+>/i',$str,$match);
echo $match[1];
//3、取height属性
preg_match('/<img.+(height=\"?\d*\"?).+>/i',$str,$match);
echo $match[1];
//4、取src
preg_match('/<img.+src=\"?(.+\.(jpg|gif|bmp|bnp|png))\"?.+>/i',$str,$match);
echo $match[1];
//1、将src="https://www.jb51.net/uploads/images/20100516000.jpg"替换为src="/uploads/uc/images/20100516000.jpg")
print preg_replace('/(<img.+src=\"?.+)(images\/)(.+\.(jpg|gif|bmp|bnp|png)\"?.+>)/i',"\${1}uc/images/\${3}",$str);
echo "<hr/>";
//2、将src="https://www.jb51.net/uploads/images/20100516000.jpg"替换为src="/uploads/uc/images/20100516000.jpg",并省去宽和高
print preg_replace('/(<img).+(src=\"?.+)images\/(.+\.(jpg|gif|bmp|bnp|png)\"?).+>/i',"\${1} \${2}uc/images/\${3}>",$str);
?>