How to remove square brackets and anything between them with a regex?

by

[ 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.

More Related Contents:

  1. PHP – Replace part of a string [closed]
  2. Get PHP to stop replacing ‘.’ characters in $_GET or $_POST arrays?
  3. remove script tag from HTML content
  4. Capturing text between square brackets in PHP
  5. get everything between and with php [duplicate]
  6. How do I remove all specific characters at the end of a string in PHP?
  7. How exactly do Regular Expression word boundaries work in PHP?
  8. How can I use .htaccess to hide .php URL extensions?
  9. PHP – regex to allow letters and numbers only
  10. Multibyte trim in PHP?
  11. preg_match() Unknown modifier ‘[‘ help
  12. Php – regular expression to check if the string has chinese chars
  13. Can someone explain the /e regex modifier? [duplicate]
  14. How do I replace double quotes with single quotes
  15. How to “Validate” Human Names in CakePHP?
  16. Function to return only alpha-numeric characters from string?
  17. In PHP, how do I extract multiple e-mail addresses from a block of text and put them into an array?
  18. How to remove diacritics from text?
  19. PHP regular expression to match lines starting with a special character
  20. Using regex to filter attributes in xpath with php
  21. Get last whole number in a string
  22. Regex to strip comments and multi-line comments and empty lines
  23. Issue with Laravel Rules & Regex (OR) operator
  24. How do I match accented characters with PHP preg?
  25. How to remove all numbers from string?
  26. Test if a string is regex
  27. Request exceeded the limit of 10 internal redirects
  28. How do I replace characters not in range [0x5E10, 0x7F35] with ‘*’ in PHP?
  29. PHP regex templating – find all occurrences of {{var}}
  30. Regex ignore URL already in HTML tags

Leave a Comment