Comparison of character APIs (GNU Gnulib)

This table summarizes the API functions available for characters, in POSIX and in Gnulib.

unibyte character	assume C locale	wide character	32-bit wide character	mbchar_t character
`== '\0'`	`== '\0'`	`== L'\0'`	`== 0`	`mb_isnul`
`==`	`==`	`==`	`==`	`mb_equal`
`isalnum`	`c_isalnum`	`iswalnum`	`c32isalnum`	`mb_isalnum`
`isalpha`	`c_isalpha`	`iswalpha`	`c32isalpha`	`mb_isalpha`
`isblank`	`c_isblank`	`iswblank`	`c32isblank`	`mb_isblank`
`iscntrl`	`c_iscntrl`	`iswcntrl`	`c32iscntrl`	`mb_iscntrl`
`isdigit`	`c_isdigit`	`iswdigit`	`c32isdigit`	`mb_isdigit`
`isgraph`	`c_isgraph`	`iswgraph`	`c32isgraph`	`mb_isgraph`
`islower`	`c_islower`	`iswlower`	`c32islower`	`mb_islower`
`isprint`	`c_isprint`	`iswprint`	`c32isprint`	`mb_isprint`
`ispunct`	`c_ispunct`	`iswpunct`	`c32ispunct`	`mb_ispunct`
`isspace`	`c_isspace`	`iswspace`	`c32isspace`	`mb_isspace`
`isupper`	`c_isupper`	`iswupper`	`c32isupper`	`mb_isupper`
`isxdigit`	`c_isxdigit`	`iswxdigit`	`c32isxdigit`	`mb_isxdigit`
–	–	`wctype`	`c32_get_type_test`	–
–	–	`iswctype`	`c32_apply_type_test`	–
`tolower`	`c_tolower`	`towlower`	`c32tolower`	–
`toupper`	`c_toupper`	`towupper`	`c32toupper`	–
–	–	`wctrans`	`c32_get_mapping`	–
–	–	`towctrans`	`c32_apply_mapping`	–
–	–	`wcwidth`	`c32width`	`mb_width`