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10.499 isblank

POSIX specification:
https://pubs.opengroup.org/onlinepubs/9699919799/functions/isblank.html

Gnulib module: isblank

Portability problems fixed by Gnulib:

• This function is missing on some platforms: Solaris 9, mingw, MSVC 9.
• This function cannot be called from plain inline or extern inline functions on some platforms: macOS 10.8.

Portability problems not fixed by Gnulib:

Note: This function’s behaviour depends on the locale, but does not support the multibyte characters that occur in strings in locales with MB_CUR_MAX > 1 (this includes all the common UTF-8 locales). There are five alternative APIs:

c_isblank

This function operates in a locale independent way and returns true only for ASCII characters. It is provided by the Gnulib module ‘c-ctype’.

iswblank

This function operates in a locale dependent way, on wide characters. In order to use it, you first have to convert from multibyte to wide characters, using the mbrtowc function. It is provided by the Gnulib module ‘wctype’.

c32isblank

This function operates in a locale dependent way, on 32-bit wide characters. In order to use it, you first have to convert from multibyte to 32-bit wide characters, using the mbrtoc32 function. It is provided by the Gnulib module ‘c32isblank’.

mb_isblank

This function operates in a locale dependent way, on multibyte characters. It is provided by the Gnulib module ‘mbchar’.

uc_is_blank

This function operates in a locale independent way, on Unicode characters. It is provided by the Gnulib module ‘unictype/ctype-blank’.