The functions provided by this extension check
whether a character or string falls into a certain
character class according to the current locale (see
also setlocale()).
When called with an integer argument these
functions behave exactly like their C counterparts from
ctype.h.
When called with a string argument they will check
every character in the string and will only return TRUE if every character in
the string matches the requested criteria. When called
with an empty string the result will always be TRUE.
Passing anything else but a string or integer will
return FALSE
immediately.
Beginning with PHP 4.2.0 these functions are
enabled by default. For older versions you have to
configure and compile PHP with
--enable-ctype. You can disable ctype support with
--disable-ctype.
The windows version of PHP
has built in support for this extension. You do not
need to load any additional extension in order to use
these functions.
注: Builtin support for ctype is available with PHP 4.3.0.