如何比较两个字符串并确定它们之间的差异？

Question

I have two strings like this:

$str1 = "this is
         a text";

$str2 = "this is a text
         which is edited";

As you see there is two difference between them, removed that <br> which is after is (in the $str1) and appending whic is edited. Now I need to detect those difference, How can I do that?

Actually I need to show to my website's users what's edited. Something exactly like stackoverflow edit page (which highlights the difference with red and green colors).

Answer 1

$Diff = str_replace($srt1, "", $str2);

Should work