Web Standards Programmer's Reference: HTML, CSS, JavaScript®, Perl, Python®, and PHP

F.7. Character Type

Function	Returns	Description
ctype_alnum(string text)	bool	Checks for alphanumeric character(s).
ctype_alpha(string text)	bool	Checks for alphabetic character(s).
ctype_cntrl(string text)	bool	Checks for control character(s).
ctype_digit(string text)	bool	Checks for numeric character(s).
ctype_graph(string text)	bool	Checks for any printable character(s) except space.
ctype_lower(string text)	bool	Checks for lowercase character(s).
ctype_print(string text)	bool	Checks for printable character(s).
ctype_punct(string text)	bool	Checks for any printable character that is not whitespace or an alphanumeric character.
ctype_space(string text)	bool	Checks for whitespace character(s).
ctype_upper(string text)	bool	Checks for uppercase character(s).
ctype_xdigit(string text)	bool	Checks for character(s) representing a hexadecimal digit.