PHP Regular Expression Reference

How it works

preg_match and preg_match_all have different count/result contracts. Replacement and splitting APIs also have their own limits and failure returns. Dynamic literal text belongs through preg_quote rather than being treated as a regex fragment. For untrusted input, choose bounded formats and input lengths; a clever pattern that takes excessive time is a poor validation boundary.

Run it locally

Run this complete source locally with PHP 8.2 or newer. Save it using the filename shown and run the command below. PHP is not currently available in Bhylu’s browser playground. Apache and MySQL are not needed for an ordinary CLI example.

php -l ref-patterns.php
php ref-patterns.php

Download this source as a local PHP lab file. Keep lab files separate from the Bhylu project and production data.

Example

<?php
declare(strict_types=1);

$literal = "Tool (small)";
$pattern = "/\A" . preg_quote($literal,"/") . "\z/";
echo preg_match($pattern,$literal) === 1 ? "Literal matched\n" : "No match\n";

Expected result

Literal matched

The parentheses are matched as literal characters instead of creating a grouping construct. Anchors require the complete input to match. The code still checks for a match explicitly rather than assuming every non-zero-like value means the same state; production callers should inspect false and diagnostics for a pattern execution error.

Contracts to check

Related API names

This alphabetic inventory helps locate related calls. Availability was checked in the review runtime; it is not a recommendation to use every API or a claim that every overload/function was executed. Read the official entry for version, extension, failure and security details.