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.
iswdigit, iswdigit_l — test for a decimal digit wide-character code
int iswdigit(wint_t wc);
int iswdigit_l(wint_t wc, locale_t locale);
For iswdigit(): 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 iswdigit() and iswdigit_l() functions shall test
whether wc is a wide-character code representing a character of class
digit 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
The behavior is undefined if the locale argument to
iswdigit_l() is the special locale object LC_GLOBAL_LOCALE or is not
a valid locale object handle.
The iswdigit() and iswdigit_l() functions shall return non-zero if
wc is a decimal digit wide-character code; otherwise, they shall return
No errors are defined.
The following sections are informative.
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.
iswalnum(), iswalpha(), iswcntrl(),
iswctype(), iswgraph(), iswlower(),
iswprint(), iswpunct(), iswspace(),
The Base Definitions volume of POSIX.1‐2017, Chapter
7, Locale, <locale.h>,
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1-2017, Standard for Information Technology -- Portable Operating
System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018
Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html .
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