Regex replace non letters with '-', but leave any periods

Question

I am trying to strip all non letters from a file path, but I need to leave the extension at the end.

File example: $text = cat.jpg

I am current using this $text = preg_replace('/[^\\\\pL\\d]+/u', '-', $text); Result: cat-jpg

But this also converts any periods to a hyphen as well, I looked around and tried what I found from other posts, but they just removed the period all together.

Help would be appreciated.

Answer 1

You can use this regex based on alternation and negative lookahead for your search:

[^\pL\pN.]+|\.(?![^.]+$)

RegEx Demo

RegEx Breakup:

[^\pL\pN.]+  # Search 1 or more of any char that is not DOT and letter and number (unicode)
|            # OR
\.           # search for DOT
(?![^.]+$)   # negative lookahead to skip DOT that is just before file extension

In PHP code:

$text = preg_replace('/[^\pL\pN.]+|\.(?![^.]+$)/u', '-', $text);