wcsnicmp.c

C标准库源代码

/***
*wcsnicmp.c - compare n chars of wide-character strings, ignoring case
*
*       Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       defines _wcsnicmp() - Compares at most n characters of two wchar_t
*       strings, without regard to case.
*
*******************************************************************************/


#include <cruntime.h>
#include <string.h>
#include <ctype.h>
#include <locale.h>
#include <setlocal.h>
#include <mtdll.h>

/***
*int _wcsnicmp(first, last, count) - compares count wchar_t of strings,
*       ignore case
*
*Purpose:
*       Compare the two strings for lexical order.  Stops the comparison
*       when the following occurs: (1) strings differ, (2) the end of the
*       strings is reached, or (3) count characters have been compared.
*       For the purposes of the comparison, upper case characters are
*       converted to lower case (wide-characters).
*
*Entry:
*       wchar_t *first, *last - strings to compare
*       size_t count - maximum number of characters to compare
*
*Exit:
*       -1 if first < last
*        0 if first == last
*        1 if first > last
*       This range of return values may differ from other *cmp/*coll functions.
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _wcsnicmp (
        const wchar_t * first,
        const wchar_t * last,
        size_t count
        )
{
        wchar_t f,l;
        int result = 0;
#if defined (_MT)
        int local_lock_flag;
#endif  /* defined (_MT) */

        if ( count ) {
            if ( __lc_handle[LC_CTYPE] == _CLOCALEHANDLE ) {
                do {
                    f = ((*first <= L'Z') && (*first >= L'A'))
                    ? *first - L'A' + L'a'
                    : *first;
                    l = ((*last <= L'Z') && (*last >= L'A'))
                    ? *last - L'A' + L'a'
                    : *last;
                    first++;
                    last++;
                } while ( (--count) && f && (f == l) );
            }
            else {
                _lock_locale( local_lock_flag )
                do {
                    f = _towlower_lk( (unsigned short)(*(first++)) );
                    l = _towlower_lk( (unsigned short)(*(last++)) );
                } while ( (--count) && f && (f == l) );
                _unlock_locale( local_lock_flag )
            }

            result = (int)(f - l);
        }
        return result;
}