How to remove square brackets and anything between them with a regex?
php, regex
Solution
`[` and `]` are special characters in a regex. They are used to list characters of a match. `[a-z]` matches any lowercase letter between `a` and `z`. `[03b]` matches a "0", "3", or "b". To match the characters `[` and `]`, you have to escape them with a preceding `\`.
Your code currently says "replace any character of `[]().` with an empty string" (reordered from the order in which you typed them for clarity).
Greedy match:
preg_replace('/\[.*\]/', '', $str); // Replace from one [ to the last ]
A greedy match could match multiple [s and ]s. That expression would take `an example [of "sneaky"] text [with more "sneaky"] here` and turn it into `an example here`.
Perl has a syntax for a non-greedy match (you most likely don't want to be greedy):
preg_replace('/\[.*?\]/', '', $str);
Non-greedy matches try to catch as few characters as possible. Using the same example: `an example [of "sneaky"] text [with more "sneaky"] here` becomes `an example text here`.
Only up to the first following ]:
preg_replace('/\[[^\]]*\]/', '', $str); // Find a [, look for non-] characters, and then a ]
This is more explicit, but harder to read. Using the same example text, you'd get the output of the non-greedy expression.
Note that none of these deal explicitly with white space. The spaces on either side of `[` and `]` will remain.
Also note that all of these can fail for malformed input. Multiple `[`s and `]`s without matches could cause a surprising result.
Problem
How can I remove text from between square brackets and the brackets themselves? For example, I need: ``` hello [quote="im sneaky"] world ``` to become: ``` hello world ``` Here's what I'm trying to use, but it's not doing the trick: ``` preg_replace("/[\[(.)\]]/", '', $str); ``` I just ended up with: ``` hello quote="im sneaky" world ```