The `quotemeta()` function in PHP escapes special characters in a string by adding a backslash before them. This is useful when you need to use a string in a regular expression or other contexts where these characters have special meaning.PHP 8.PHP 8.1,PHP 8.2,PHP 8.3 and PHP 8.4.

Example Usage in PHP 8.2<?php$originalString = "Hello. This costs $10 (cheap)! Got it? [Yes]";$escapedString = quotemeta($originalString);echo "Original string: " . $originalString . "\n";echo "Escaped string: " . $escapedString . "\n";?>

Output:

Original string: Hello. This costs $10 (cheap)! Got it? [Yes]Escaped string: Hello\. This costs \$10 \(cheap\)\! Got it\? \[Yes\]

Practical Use CaseThis function is particularly useful when you want to use user input in regular expression<?php$userInput = "file.*.txt"; // User might input something with special regex chars$pattern = "/^" . quotemeta($userInput) . "$/";// Now $pattern is "/^file\.\*\.txt$/", which will match the literal string// instead of treating .* as regex wildcardsif (preg_match($pattern, "file.*.txt")) {echo "Match found!";} else {echo "No match.";}Notes for PHP 8.21. The behavior of `quotemeta()` hasn't changed in PHP 8.2 - it works the same as in previous versions.2. For more complex escaping needs in regular expressions, consider using `preg_quote()` which allows you to specify an additional delimiter character to escape.3. Remember that `quotemeta()` doesn't escape all possible special characters in every context - it's designed for a specific set of metacharacters.