(PHP 4 >= 4.0.6, PHP 5, PHP 7) Set/Get substitution character

(PHP 4 >= 4.0.6, PHP 5, PHP 7) Decode string in MIME header field

(PHP 4 >= 4.3.0, PHP 5, PHP 7) Make a string uppercase

(PHP 5 >= 5.2.0, PHP 7) Finds the last occurrence of a character in a string within another, case insensitive

(PHP 4 >= 4.0.6, PHP 5, PHP 7) Convert character encoding

(PHP 4 >= 4.0.6, PHP 5, PHP 7) Detect character encoding

(PHP 5 >= 5.2.0, PHP 7) Finds first occurrence of a string within another, case insensitive

(PHP 4 >= 4.2.0, PHP 5, PHP 7) Returns start point for next regular expression match

(PHP 5 >= 5.2.0, PHP 7) Finds position of last occurrence of a string within another, case insensitive

(PHP 4 >= 4.2.0, PHP 5, PHP 7) Returns position and length of a matched part of the multibyte regular expression