在条件下替换字符串（正则表达式？）

Question

I am looking for a solution for search and replace. I would need to add an empty space after specific string BUT only if there isn't one already. Regular expressions are to advanced for me. Anyone wants to help me out?

For example

Lorem ipsum[something]abcdefg[/something]dolor sit amet

Needs to be replace with

Lorem ipsum[something]abcdefg[/something] dolor sit amet

So, I need to search for [/something] and if it is not followed by space, then do the replace...

Answer 1

The regular expression can be this:

/(\[\/something\])(?!\s)/gmi

You can test it and know the whole explanation here:

https://regex101.com/r/pC4pQ3/1

If you see the first is targetted because is not an space, but the second is the opposite.

To apply this in PHP you must to use preg_replace() . Something like this:

$string = "Lorem ipsum[something]abcdefg[/something]dolor sit amet";
echo preg_replace("/(\[\/something\])(?!\s)/", "\1 ", $string);
// result: "Lorem ipsum[something]abcdefg[/something] dolor sit amet"