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The header <wctype.h> provides the prototypes for the wide-character functions that support character classification. These functions categorize wide characters as to their type or convert the case of a character. The following table lists these functions along with their char equivalents, which are described in Chapter 7.
Function | char Equivalent |
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int iswalnum(wint_t ch) | isalnum( ) |
int iswalpha(wint_t ch) | isalpha( ) |
int iswblank(wint_t ch) | isblank( ) (Added by C99) |
int iswcntrl(wint_t ch) | iscntrl( ) |
int iswdigit(wint_t ch) | isdigit( ) |
int iswgraph(wint_t ch) | isgraph( ) |
int iswlower(wint_t ch) | islower( ) |
int iswprint(wint_t ch) | isprint( ) |
int iswpunct(wint_t c) | ispunct( ) |
int iswspace(wint_t ch) | isspace( ) |
int iswupper(wint_t ch) | isupper( ) |
int iswxdigit(wint_t ch) | isxdigit( ) |
wint_t towlower(wint_t ch) | tolower( ) |
wint_t towupper(wint_t ch) | toupper( ) |
In addition to the functions shown above, <wctype.h> defines the following, which provide an open-ended means of classifying characters:
wctype_t wctype(const char *attr);
int iswctype(wint_t ch, wctype_t attr_ob);
The function wctype( ) returns a value that can be passed as the attr_ob parameter to iswctype( ). The string pointed to by attr specifies a property that a character must have. This value can then be used to determine if ch is a character that has that property. If it has, iswctype( ) returns nonzero. Otherwise, it returns zero. The following property strings are defined for all execution environments:
alnum | alpha | cntrl | digit |
graph | lower | | punct |
space | upper | xdigit |
For C99, the string “blank” is also defined.
The functions wctrans( ) and towctrans( ) are also defined in <wctype.h>. They are shown here:
wctrans_t wctrans(const char *mapping);
wint_t towctrans(wint_t ch, wctrans_t mapping_ob);
The function wctrans( ) returns a value that can be passed as the mapping_ob parameter to towctrans( ). The string pointed to by mapping specifies a mapping of one character to another. This value can then be used by towctrans( ) to map ch. The mapped value is returned. The following mapping strings are supported in all execution environments:
tolower | toupper |
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