(PHP 4, PHP 5, PHP 7) Return array entries that match the pattern

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

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

(PHP 4, PHP 5, PHP 7) Alias of

(PHP 4, PHP 5) Replace regular expression case insensitive

(PHP 4, PHP 5, PHP 7) Calculate the md5 hash of a string

(PHP 4 >= 4.3.0, PHP 5, PHP 7) Return information about words used in a string

(PHP 4 >= 4.0.5, PHP 5, PHP 7) Perform a regular expression search and replace using a callback

(PHP 4, PHP 5, PHP 7) Binary safe string comparison

(PHP 4, PHP 5, PHP 7) Make a string's first character uppercase