(PHP 4, PHP 5, PHP 7) Case-insensitive

(PHP 4 >= 4.0.2, PHP 5, PHP 7) Wraps a string to a given number of characters

(PHP 5, PHP 7) Search a string for any of a set of characters

(PHP 4, PHP 5, PHP 7) Quote meta characters string

(PHP 4, PHP 5, PHP 7) Convert all applicable characters to HTML entities

(PHP 4, PHP 5, PHP 7) Convert from one Cyrillic character set to another

(PHP 4, PHP 5, PHP 7) Case insensitive string comparisons using a "natural order" algorithm

(PHP 4, PHP 5, PHP 7) Join array elements with a string

(PHP 4, PHP 5, PHP 7) Translate characters or replace substrings

(PHP 4, PHP 5, PHP 7) Calculate the similarity between two strings