(PHP 4, PHP 5, PHP 7) Make a string lowercase

(PHP 5 >= 5.3.0, PHP 7) Parse a CSV string into an array

(PHP 4, PHP 5) Case insensitive regular expression match

(PHP 4 >= 4.3.0, PHP 5, PHP 7) Formats a number as a currency string

(PHP 4 >= 4.3.0, PHP 5, PHP 7) Calculate the sha1 hash of a string

(PHP 4, PHP 5, PHP 7) Return information about characters used in a string

(PECL ssdeep >= 1.0.0) Create a fuzzy hash from a string

(PECL bbcode >= 0.9.0) Parse a string following a given rule set

(PHP 7) Perform a regular expression search and replace using callbacks

(PHP 4 >= 4.0.5, PHP 5, PHP 7) Get numeric formatting information