mbsstr.c

C标准库源代码

/***
* mbsstr.c - Search for one MBCS string inside another
*
*       Copyright (c) 1988-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       Search for one MBCS string inside another
*
*******************************************************************************/

#ifdef _MBCS

#include <cruntime.h>
#include <mbdata.h>
#include <mbctype.h>
#include <mbstring.h>
#include <stddef.h>
#include <string.h>

#define _BYTELEN(s)     (strlen(s))
#define _MBSINC(s)      (_mbsinc(s))
#define PCHAR           char *

/***
* _mbsstr - Search for one MBCS string inside another
*
*Purpose:
*       Find the first occurrence of str2 in str1.
*
*Entry:
*       unsigned char *str1 = beginning of string
*       unsigned char *str2 = string to search for
*
*Exit:
*       Returns a pointer to the first occurrence of str2 in
*       str1, or NULL if str2 does not occur in str1
*
*Exceptions:
*
*******************************************************************************/

unsigned char * __cdecl _mbsstr(
        const unsigned char *str1,
        const unsigned char *str2
        )
{
        unsigned char *cp, *s1, *s2, *endp;

        if ( _ISNOTMBCP )
                return strstr(str1, str2);

        cp = (unsigned char *) str1;
        endp = (unsigned PCHAR) (str1 + (_BYTELEN(str1) - _BYTELEN(str2)));

        while (*cp && (cp <= endp))
        {
                s1 = cp;
                s2 = (PCHAR) str2;

                /*
                 * MBCS: ok to ++ since doing equality comparison.
                 * [This depends on MBCS strings being "legal".]
                 */

                while ( *s1 && *s2 && (*s1 == *s2) )
                        s1++, s2++;

                if (!(*s2))
                        return(cp);     /* success! */

                /*
                 * bump pointer to next char
                 */

                cp = _MBSINC(cp);

        }

        return(NULL);

}

#endif  /* _MBCS */