The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.
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iswctype - test character for a specified class


#include <wctype.h>

int iswctype(wint_t
wc, wctype_t charclass);


[CX] [Option Start] 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 IEEE Std 1003.1-2001 defers to the ISO C standard. [Option End]

The iswctype() function shall determine whether the wide-character code wc has the character class charclass, returning true or false. The iswctype() function is defined on WEOF and wide-character codes corresponding to the valid character encodings in the current locale. 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 iswctype() function shall return non-zero (true) if and only if wc has the property described by charclass. [CX] [Option Start]  If charclass is 0, iswctype() shall return 0. [Option End]


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. */


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"))
iswalpha(wc)    iswctype(wc, wctype("alpha"))
iswblank(wc)    iswctype(wc, wctype("blank"))
iswcntrl(wc)    iswctype(wc, wctype("cntrl"))
iswdigit(wc)    iswctype(wc, wctype("digit"))
iswgraph(wc)    iswctype(wc, wctype("graph"))
iswlower(wc)    iswctype(wc, wctype("lower"))
iswprint(wc)    iswctype(wc, wctype("print"))
iswpunct(wc)    iswctype(wc, wctype("punct"))
iswspace(wc)    iswctype(wc, wctype("space"))
iswupper(wc)    iswctype(wc, wctype("upper"))
iswxdigit(wc)   iswctype(wc, wctype("xdigit"))






iswalnum(), iswalpha(), iswcntrl(), iswdigit(), iswgraph(), iswlower(), iswprint(), iswpunct(), iswspace(), iswupper(), iswxdigit(), setlocale(), wctype(), the Base Definitions volume of IEEE Std 1003.1-2001, <wchar.h>, <wctype.h>


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

Issue 5

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

Issue 6

The behavior of n=0 is now described.

An example is added.

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

End of informative text.

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