iswblank - Man Page

test for a blank wide-character code


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.


#include <wctype.h>

int iswblank(wint_t wc);
int iswblank_l(wint_t wc, locale_t locale);


For iswblank(): The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO C standard.

The iswblank() and iswblank() functions shall test whether wc is a wide-character code representing a character of class blank in the current locale, or in the locale represented by locale, respectively; see the Base Definitions volume of POSIX.1-2017, Chapter 7, Locale.

The wc argument is a wint_t, the value of which the application shall ensure is a wide-character code corresponding to a valid character in the locale used by the function, or equal to the value of the macro WEOF. If the argument has any other value, the behavior is undefined.

The behavior is undefined if the locale argument to iswblank_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.

Return Value

The iswblank() and iswblank_l() functions shall return non-zero if wc is a blank wide-character code; otherwise, they shall return 0.


No errors are defined.

The following sections are informative.



Application Usage

To ensure applications portability, especially across natural languages, only these functions and the functions in the reference pages listed in the See Also section should be used for character classification.



Future Directions


See Also

iswalnum(), iswalpha(), iswcntrl(), iswctype(), iswdigit(), iswgraph(), iswlower(), iswprint(), iswpunct(), iswspace(), iswupper(), iswxdigit(), setlocale(), uselocale()

The Base Definitions volume of POSIX.1-2017, Chapter 7, Locale, <locale.h>, <wctype.h>

Referenced By

setlocale(3p), wctype.h(0p).

2017 IEEE/The Open Group POSIX Programmer's Manual