iswalpha(3)

iswalpha3

Test for alphabetic wide character

Usage

#include <wctype.h>

int iswalpha(wint_t wc);

Library

Standard C library (libc, -lc)

Overview

The iswalpha() function is the wide-character equivalent of the isalpha(3) function. It tests whether wc is a wide character belonging to the wide-character class "alpha".

The wide-character class "alpha" is a subclass of the wide-character class "alnum", and therefore also a subclass of the wide-character class "graph" and of the wide-character class "print".

Being a subclass of the wide-character class "print", the wide-character class "alpha" is disjoint from the wide-character class "cntrl".

Being a subclass of the wide-character class "graph", the wide-character class "alpha" is disjoint from the wide-character class "space" and its subclass "blank".

Being a subclass of the wide-character class "alnum", the wide-character class "alpha" is disjoint from the wide-character class "punct".

The wide-character class "alpha" is disjoint from the wide-character class "digit".

The wide-character class "alpha" contains the wide-character classes "upper" and "lower".

The wide-character class "alpha" always contains at least the letters 'A' to 'Z' and 'a' to 'z'.

Return value

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

Attributes

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

InterfaceAttributeValue
iswalpha()Thread safetyMT-Safe locale

Notes

The behavior of iswalpha() 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

C11, POSIX.1-2008.

History

POSIX.1-2001, C99.

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