(PHP 4 >= 4.0.2, PHP 5, PHP 7) Binary safe case-insensitive string comparison of the first n characters

(PHP 4, PHP 5) Regular expression match int ereg

(PHP 4 >= 4.0.1, PHP 5, PHP 7) Calculate Levenshtein distance between two strings

(PHP 4, PHP 5, PHP 7) Convert binary data into hexadecimal representation

(PECL bbcode >= 0.10.2) Adds a smiley to the parser

(PHP 4, PHP 5) Replace regular expression string

(PHP 4, PHP 5, PHP 7) Replace all occurrences of the search string with the replacement string

(PHP 5 >= 5.1.0, PHP 7) Convert special HTML entities back to characters

(PHP 4, PHP 5, PHP 7) Returns the translation table used by htmlspecialchars()

(PHP 4, PHP 5, PHP 7) Strip HTML and PHP tags from a string