Using Regex to detect if string exists

Question

I need to use PHP's preg_match() and Regex to detect the following conditions:

If a URL path is one of the following:

products/new items
new items/products
new items/products/brand name

Do something...

I can't seem to figure out how to check if the a string exists before or after the word products. The closest I can get is:

if (preg_match("([a-zA-Z0-9_ ]+)\/products\/([a-zA-Z0-9_ ]+)", $url_path)) {
  // Do something

Would anyone know a way to check if the first part of the string exists within the one regex line?

You can use alternation ([\w_ ]+)\/products|products\/([\w_ ]+) — Code Maniac
– Code Maniac, Commented Sep 2, 2019 at 6:47

The fourth bird · Accepted Answer · 2019-09-02 06:53:12Z

1

You could use an alternation with an optional group for the last item making the / part of the optional group.

If you are only looking for a match, you can omit the capturing groups.

(?:[a-zA-Z0-9_ ]+/products(?:/[a-zA-Z0-9_ ]+)?|products/[a-zA-Z0-9_ ]+)

Explanation

(?: Non catpuring group
- [a-zA-Z0-9_ ]+/products Match 1+ times what is listed in the character class, / followed by products
- (?:/[a-zA-Z0-9_ ]+)? Optionally match / and what is listed in the character class
- | Or
- products/[a-zA-Z0-9_ ]+ Match products/, match 1+ times what is listed
) Close group

Regex demo

Note that [a-zA-Z0-9_ ]+ might be shortened to [\w ]+

edited Sep 2, 2019 at 6:53

answered Sep 2, 2019 at 6:47

The fourth bird

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3 Comments

MeltingDog Over a year ago

This is odd, when I implement it with words other than "product" (as my site requires) it only detects the first instance, eg regex101.com/r/0KfEjo/1

The fourth bird Over a year ago

@MeltingDog You have to enable the global flag g at the right top on regex101 regex101.com/r/0KfEjo/2

Wiktor Stribiżew Over a year ago

@MeltingDog But surely do not use any g modifier in PHP code.

Code Maniac · Accepted Answer · 2019-09-02 06:48:40Z

1

You can use alternation

([\w ]+)\/products|products\/([\w ]+)

Regex Demo

Note:- I am not sure how you're using the matched values, if you don't need back reference to any specific values then you can avoid capturing group, i.e.

 [\w ]+\/products|products\/[\w ]+

answered Sep 2, 2019 at 6:48

Code Maniac

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