NAME

iswctype, iswctype_l — test character for a specified class

SYNOPSIS

#include <wctype.h>

int iswctype(wint_t wc, wctype_t charclass);


[CX] int iswctype_l(wint_t wc, wctype_t charclass,
       locale_t locale);

DESCRIPTION

For iswctype(): ^[CX]  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.1-2024 defers to the ISO C standard.

The iswctype() ^[CX]  and iswctype_l()  functions shall determine whether the wide-character code wc has the character class charclass, returning true or false. The iswctype() ^[CX]  and iswctype_l() functions are defined on WEOF and wide-character codes corresponding to the valid character encodings in the current locale, or ^[CX]  in the locale represented by locale, respectively. If the wc argument is not in the domain of the function, the result is undefined. If the value of charclass is invalid (that is, not obtained by a call to wctype() or charclass is invalidated by a subsequent call to setlocale() that has affected category LC_CTYPE ) the result is unspecified.

^[CX] The behavior is undefined if the locale argument to iswctype_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.

RETURN VALUE

The iswctype() ^[CX]  and iswctype_l()  functions shall return non-zero (true) if and only if wc has the property described by charclass. If charclass is (wctype_t)0, the iswctype() ^[CX]  and iswctype_l() functions shall return 0.

ERRORS

No errors are defined.

EXAMPLES

Testing for a Valid Character

#include <wctype.h>
...
int yes_or_no;
wint_t wc;
wctype_t valid_class;
...
if ((valid_class=wctype("vowel")) == (wctype_t)0)
    /* Invalid character class. */
yes_or_no=iswctype(wc,valid_class);

APPLICATION USAGE

The twelve strings "alnum", "alpha", "blank", "cntrl", "digit", "graph", "lower", "print", "punct", "space", "upper", and "xdigit" are reserved for the standard character classes. In the table below, the functions in the left column are equivalent to the functions in the right column.

iswalnum(wc)            iswctype(wc, wctype("alnum"))
iswalnum_l(wc, locale)  iswctype_l(wc, wctype("alnum"), locale)
iswalpha(wc)            iswctype(wc, wctype("alpha"))
iswalpha_l(wc, locale)  iswctype_l(wc, wctype("alpha"), locale)
iswblank(wc)            iswctype(wc, wctype("blank"))
iswblank_l(wc, locale)  iswctype_l(wc, wctype("blank"), locale)
iswcntrl(wc)            iswctype(wc, wctype("cntrl"))
iswcntrl_l(wc, locale)  iswctype_l(wc, wctype("cntrl"), locale)
iswdigit(wc)            iswctype(wc, wctype("digit"))
iswdigit_l(wc, locale)  iswctype_l(wc, wctype("digit"), locale)
iswgraph(wc)            iswctype(wc, wctype("graph"))
iswgraph_l(wc, locale)  iswctype_l(wc, wctype("graph"), locale)
iswlower(wc)            iswctype(wc, wctype("lower"))
iswlower_l(wc, locale)  iswctype_l(wc, wctype("lower"), locale)
iswprint(wc)            iswctype(wc, wctype("print"))
iswprint_l(wc, locale)  iswctype_l(wc, wctype("print"), locale)
iswpunct(wc)            iswctype(wc, wctype("punct"))
iswpunct_l(wc, locale)  iswctype_l(wc, wctype("punct"), locale)
iswspace(wc)            iswctype(wc, wctype("space"))
iswspace_l(wc, locale)  iswctype_l(wc, wctype("space"), locale)
iswupper(wc)            iswctype(wc, wctype("upper"))
iswupper_l(wc, locale)  iswctype_l(wc, wctype("upper"), locale)
iswxdigit(wc)           iswctype(wc, wctype("xdigit"))
iswxdigit_l(wc, locale) iswctype_l(wc, wctype("xdigit"), locale)

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

iswalnum, iswalpha, iswcntrl, iswdigit, iswgraph, iswlower, iswprint, iswpunct, iswspace, iswupper, iswxdigit, setlocale, uselocale, wctype

XBD <locale.h>, <wctype.h>

CHANGE HISTORY

First released as World-wide Portability Interfaces in Issue 4.

Issue 5

The following change has been made in this version for alignment with ISO/IEC 9899:1990/Amendment 1:1995 (E):

• The SYNOPSIS has been changed to indicate that this function and associated data types are now made visible by inclusion of the <wctype.h> header rather than <wchar.h>.

Issue 6

The behavior of charclass = (wctype_t)0 is now described.

An example is added.

A new function, iswblank(), is added to the list in the APPLICATION USAGE.

Issue 7

The iswctype_l() function is added from The Open Group Technical Standard, 2006, Extended API Set Part 4.

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0321 [283] and XSH/TC1-2008/0322 [283] are applied.

POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0184 [799] and XSH/TC2-2008/0185 [799] are applied.

Issue 8

Austin Group Defect 1302 is applied, aligning the iswctype() function with the ISO/IEC 9899:2018 standard.