说明
bool
ctype_alpha ( string text )
Checks if all of the characters in the provided string,
text, are alphabetic.
In the standard C locale letters are just
[A-Za-z] and ctype_alpha() is
equivalent to (ctype_upper($text) || ctype_lower($text))
if $text is just a single character, but other languages have letters that
are considered neither upper nor lower case.