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

(PHP 4, PHP 5, PHP 7) Count the number of substring occurrences

(PHP 4, PHP 5, PHP 7) Reverse a string string

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

(PHP 4, PHP 5, PHP 7) String comparisons using a "natural order" algorithm

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

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

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

(PHP 4, PHP 5, PHP 7) Set locale information

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