iswctype man page


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.

iswctype, iswctype_l — test character for a specified class


#include <wctype.h>

int iswctype(wint_t wc, wctype_t charclass);
int iswctype_l(wint_t wc, wctype_t charclass,
    locale_t locale);


For iswctype(): 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.1‐2008 defers to the ISO C standard.

The iswctype() and iswctype_l() functions shall determine whether the wide-character code wc has the character class charclass, returning true or false. The iswctype() and iswctype_l() functions are defined on WEOF and wide-character codes corresponding to the valid character encodings in the current locale, or 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.

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() and iswctype_l() functions shall return non-zero (true) if and only if wc has the property described by charclass. If charclass is 0, these functions shall return 0.


No errors are defined.

The following sections are informative.


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. */

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)

See Also

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

The Base Definitions volume of POSIX.1‐2008, <locale.h>, <wctype.h>