Regex for IMG filename

Question

I want to test if a img filename (jpg) is valid in PHP. The files should look like this:

test-file.jpg

test-123-test.jpg

123-456-thumbnail.jpg

I tried the following regex:

([a-z0–9-])+.(jpg)

It works fine, but still allows filnames like "test--123----.jpg", but I just want to allow one "-".

Any idea how to solve this?

Does this answer your question? [Regex to disallow more than 1 dash consecutively](https://stackoverflow.com/questions/4897353/regex-to-disallow-more-than-1-dash-consecutively) — Nico Haase, Sep 28 '21 at 05:29

score 2 · Accepted Answer · answered Sep 28 '21 at 05:33

2

I would phrase the regex as:

^[a-z0-9]+(?:-[a-z0-9]+)*\.jpg$

Demo

This expresses a filename having one or more terms, each separated by a single hyphen.

answered Sep 28 '21 at 05:33

Tim Biegeleisen

score 1 · Answer 2 · answered Sep 28 '21 at 05:35

1

I would go with something like this.

^(\w+([-]{1})?)+[.]jpg$

Here is a link for test purpose : https://regex101.com/r/Fo7b9c/1/

answered Sep 28 '21 at 05:35

Baldráni

1

this can also be like `^(\w+-?)+\.jpg$` no need of `{1}` here – Ghost Ops Sep 28 '21 at 05:36
Indeed, it was just a proposition but there is hundreds of way of solving that I guess. – Baldráni Sep 28 '21 at 05:37