Determines whether a character is alphabetic (i.e. a letter).
Unlike the standard C library isalpha() function, this only
recognizes standard ASCII letters and ignores the locale,
returning FALSE for all non-ASCII characters. Also, unlike
the standard library function, this takes a char,
not an int, so don't call it on EOF, but no need to
cast to guchar before passing a possibly non-ASCII character in.
Determines whether a character is alphabetic (i.e. a letter). Unlike the standard C library isalpha() function, this only recognizes standard ASCII letters and ignores the locale, returning FALSE for all non-ASCII characters. Also, unlike the standard library function, this takes a char, not an int, so don't call it on EOF, but no need to cast to guchar before passing a possibly non-ASCII character in.