ISWCTYPE(3) Library Functions Manual ISWCTYPE(3)

iswctype — test character for a specified class

#include <wctype.h>

int iswctype(wint_t wc, wctype_t charclass);

[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 IEEE Std 1003.1-2001 (“POSIX.1”) defers to the ISO C standard.

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(3) or charclass is invalidated by a subsequent call to setlocale(3) that has affected category the result is unspecified.

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

No errors are defined.

#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);

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"))

None.

None.

iswalnum(3) , iswalpha(3) , iswcntrl(3) , iswdigit(3) , iswgraph(3) , iswlower(3) , iswprint(3) , iswpunct(3) , iswspace(3) , iswupper(3) , iswxdigit(3) , setlocale(3) , wctype(3) , the Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), <wchar.h>, <wctype.h>

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

The following change has been made in this issue for alignment with ISO/IEC 9899/AMD1:1995 (“ISO C90, Amendment 1”) (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>.

The behavior of =0 is now described.

An example is added.

A new function, iswblank(3), is added to the list in the APPLICATION USAGE.

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December 6, 2001 posix.fail