(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) Convert all applicable characters to HTML entities

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

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

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

(PHP 4 >= 4.0.1, PHP 5, PHP 7) Parses input from a string according to a format

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

(PHP 5, PHP 7) Find the position of the first occurrence of a case-insensitive substring in a string

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