#include <wchar.h> int wcscasecmp(const wchar_t *ws1, const wchar_t *ws2); int wcscasecmp_l(const wchar_t *ws1, const wchar_t *ws2, locale_t locale); int wcsncasecmp(const wchar_t *ws1, const wchar_t *ws2, size_t n); int wcsncasecmp_l(const wchar_t *ws1, const wchar_t *ws2, size_t n, locale_t locale);
The wcscasecmp() and wcscasecmp_l() functions shall compare, while ignoring differences in case, the wide-character string pointed to by ws1 to the wide-character string pointed to by ws2.
The wcsncasecmp() and wcsncasecmp_l() functions shall compare, while ignoring differences in case, not more than n wide-characters from the wide-character string pointed to by ws1 to the wide-character string pointed to by ws2.
The wcscasecmp() and wcsncasecmp() functions use the current locale to determine the case of the wide characters.
The wcscasecmp_l() and wcsncasecmp_l() functions use the locale represented by locale to determine the case of the wide characters.
When the LC_CTYPE category of the locale being used is from the POSIX locale, these functions shall behave as if the wide-character strings had been converted to lowercase and then a comparison of wide-character codes performed. Otherwise, the results are unspecified.
The information for wcscasecmp_l() and wcsncasecmp_l() about the case of the characters comes from the locale represented by locale.
The behavior is undefined if the locale argument to wcscasecmp_l() or wcsncasecmp_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.
Upon completion, the wcsncasecmp() and wcsncasecmp_l() functions shall return an integer greater than, equal to, or less than 0 if the possibly null wide-character terminated string pointed to by ws1 is, ignoring case, greater than, equal to, or less than the possibly null wide-character terminated string pointed to by ws2, respectively.
No return values are reserved to indicate an error.
The following sections are informative.
The Base Definitions volume of POSIX.1-2017, <wchar.h>
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