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

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

(PHP 4 >= 4.0.6, PHP 5, PHP 7) Convert "kana" one from another ("zen-kaku", "han-kaku" and more)

(PHP 4 >= 4.0.6, PHP 5, PHP 7) Return width of string

(PHP 4 >= 4.0.6, PHP 5, PHP 7) Find position of first occurrence of string in a string

(PHP 4 >= 4.3.0, PHP 5, PHP 7) Count the number of substring occurrences

(PHP 4 >= 4.2.0, PHP 5, PHP 7) Replace regular expression with multibyte support

(PHP 4 >= 4.0.6, PHP 5, PHP 7) Send encoded mail

(PHP 4 >= 4.3.0, PHP 5, PHP 7) Perform case folding on a string

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