iswblank(3)

iswblank3

Test for whitespace wide character

Usage

#include <wctype.h>

int iswblank(wint_t wc);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

iswblank():

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

Library

Standard C library (libc, -lc)

Overview

The iswblank() function is the wide-character equivalent of the isblank(3) function. It tests whether wc is a wide character belonging to the wide-character class "blank".

The wide-character class "blank" is a subclass of the wide-character class "space".

Being a subclass of the wide-character class "space", the wide-character class "blank" is disjoint from the wide-character class "graph" and therefore also disjoint from its subclasses "alnum", "alpha", "upper", "lower", "digit", "xdigit", "punct".

The wide-character class "blank" always contains at least the space character and the control character '\t'.

Return value

The iswblank() function returns nonzero if wc is a wide character belonging to the wide-character class "blank". Otherwise, it returns zero.

Attributes

For an explanation of the terms used in this section, see attributes(7).

InterfaceAttributeValue
iswblank()Thread safetyMT-Safe locale

Notes

The behavior of iswblank() depends on the LC_CTYPE category of the current locale.

Releases

14 releases since Debian 2.2 (Potato); the text changed 13 times.

  1. 2.2
  2. 3.0
  3. 3.1
  4. 4.0
  5. 5.0
  6. 6.0
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12
  13. 13
  14. Arch

Standards

POSIX.1-2008.

History

POSIX.1-2001.

From man-pages 6.19-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.