详细版：

PHP正则提取或更改图片img标记中的任意属性';

//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
preg_match('//i',$str,$match);
echo $match[1];

//3、取height
preg_match('//i',$str,$match);
echo $match[1];

//4、取src
preg_match('//i',$str,$match);
echo $match[1];

/*PHP正则替换图片img标记中的任意属性*/
//1、将src="/uploads/images/20100516000.jpg"替换为src="/uploads/uc/images/2017020716154162.jpg")
print preg_replace('/()/i',"\${1}uc/images/\${3}",$str);
echo "
";

//2、将src="/uploads/images/20100516000.jpg"替换为src="/uploads/uc/images/2017020716154162.jpg",并省去宽和高
print preg_replace('/(/i',"\${1} \${2}uc/images/\${3}>",$str);
?>