_mbsdec, _mbsdec_l, _strdec, _wcsdec

Статья
10/16/2008

Moves a string pointer back one character.

unsigned char *_mbsdec(
   const unsigned char *start,
   const unsigned char *current 
);
unsigned char *_mbsdec_l(
   const unsigned char *start,
   const unsigned char *current,
   _locale_t locale
);

Параметры

start
Pointer to first byte of any multibyte character in the source string; start must precede current in the source string.
current
Pointer to first byte of any multibyte character in the source string; current must follow start in the source string.
locale
Locale to use.

Возвращаемое значение

_mbsdec, _mbsdec_l,_strdec, and _wcsdec each return a pointer to the character that immediately proceeds current; _mbsdec returns NULL if the value of start is greater than or equal to that of current. _tcsdec maps to one of these functions and its return value depends on the mapping.

Заметки

The _mbsdec and _mbsdec_l function returns a pointer to the first byte of the multibyte character that immediately precedes current in the string that contains start.

The output value is affected by the setting of the LC_CTYPE category setting of the locale; see setlocale for more information. _mbsdec recognizes multibyte-character sequences according to the local currently in use, while _mbsdec_lis identical except that it use the locale parameter passed in instead. For more information, see Locale.

If start or current is NULL, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, this function returns EINVAL and sets errno to EINVAL.

Security Note This API incurs a potential threat brought about by a buffer overrun problem. Buffer overrun problems are a frequent method of system attack, resulting in an unwarranted elevation of privilege. For more information, see Avoiding Buffer Overruns.

Generic-Text Routine Mappings

Tchar.h routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
_tcsdec	_strdec	_mbsdec	_wcsdec

_strdec and _wcsdec are single-byte character and wide-character versions of _mbsdec and _mbsdec_l. _strdec and _wcsdec are provided only for this mapping and should not be used otherwise.

For more information, see Using Generic-Text Mappings and Generic-Text Mappings.

Требования

Routine	Required header	Optional header
_mbsdec	<mbstring.h>	<mbctype.h>
_mbsdec_l	<mbstring.h>	<mbctype.h>
_strdec	<tchar.h>
_wcsdec	<tchar.h>

For more compatibility information, see Compatibility in the Introduction.

Пример

The following code snippet shows a use of _tcsdec.

   const TCHAR *str = _T("some text");
   const TCHAR *str2;
   TCHAR *answer;
   str2 = str;
   str2++;
   answer = _tcsdec( str, str2 );

The following code snippet shows a use of _mbsdec.

   char *str = "some text";
   char *str2;
   unsigned char *answer;
   str2 = str; 
   str2++;
   answer = _mbsdec( reinterpret_cast<unsigned char *>( str ), reinterpret_cast<unsigned char *>( str2 ));