_stat, _wstat Functions

مقالة
06/30/2010

Get status information on a file.

int _stat(
   const char *path,
   struct _stat *buffer 
);
int _stat32(
   const char *path,
   struct __stat32 *buffer 
);
int _stat64(
   const char *path,
   struct __stat64 *buffer 
);
int _stati64(
   const char *path,
   struct _stati64 *buffer 
);
int _stat32i64(str
   const char *path,
      struct _stat32i64 *buffer 
);
int _stat64i32(str
      const char *path,
   struct _stat64i32 *buffer 
);
int _wstat(
   const wchar_t *path,
   struct _stat *buffer 
);
int _wstat32(
   const wchar_t *path,
   struct __stat32 *buffer 
);
int _wstat64(
   const wchar_t *path,
   struct __stat64 *buffer 
);
int _wstati64(
   const wchar_t *path,
   struct _stati64 *buffer 
);
int _wstat32i64(
   const wchar_t *path,
   struct _stat32i64 *buffer 
);
int _wstat64i32(
   const wchar_t *path,
   struct _stat64i32 *buffer 
);

Parámetros

path
Pointer to a string containing the path of existing file or directory.
buffer
Pointer to structure that stores results.

Valor devuelto

Each of these functions returns 0 if the file-status information is obtained.A return value of –1 indicates an error, in which case errno is set to ENOENT, indicating that the filename or path could not be found.A return value of EINVAL indicates an invalid parameter; errno is also set to EINVAL in this case.

ملاحظة

If path contains the location of a directory, it cannot contain a trailing backslash.If it does, -1 will be returned and errno will be set to ENOENT.

See _doserrno, errno, _sys_errlist, and _sys_nerr for more information on this, and other, return codes.

The date stamp on a file can be represented if it is later than midnight, January 1, 1970, and before 23:59:59, December 31, 3000, UTC, unless you use _stat32 or _wstat32, or have defined _USE_32BIT_TIME_T, in which case the date can be represented only until 03:14:07 January 19, 2038, UTC.

Comentarios

The _stat function obtains information about the file or directory specified by path and stores it in the structure pointed to by buffer._stat automatically handles multibyte-character string arguments as appropriate, recognizing multibyte-character sequences according to the multibyte code page currently in use.

_wstat is a wide-character version of _stat; the path argument to _wstat is a wide-character string._wstat and _stat behave identically except that _wstat does not handle multibyte-character strings.

Variations of these functions support 32- or 64-bit time types, and 32- or 64-bit file lengths.The first numerical suffix (32 or 64) indicates the size of the time type used; the second suffix is either i32 or i64, indicating whether the file size is represented as a 32-bit or 64-bit integer.

In Visual C++ 2005, _stat is equivalent to _stat64i32, and struct _stat contains a 64-bit time.This is true unless _USE_32BIT_TIME_T is defined, in which case the old behavior is in effect; _stat uses a 32-bit time, and struct _stat contains a 32-bit time.The same is true for _stati64.

ملاحظة

_wstat does not work with Windows Vista symbolic links.In these cases, _wstat will always report a file size of 0._stat does work correctly with symbolic links.

This function validates its parameters.If either path or buffer is NULL, the invalid parameter handler is invoked, as described in Parameter Validation.

Time Type and File Length Type Variations of _stat

Functions	_USE_32BIT_TIME_T defined?	Time type	File length type
_stat, _wstat	Not defined	64-bit	32-bit
_stat, _wstat	Defined	32-bit	32-bit
_stat32, _wstat32	Not affected by the macro definition	32-bit	32-bit
_stat64, _wstat64	Not affected by the macro definition	64-bit	64-bit
_stati64, _wstati64	Not defined	64-bit	64-bit
_stati64, _wstati64	Defined	32-bit	64-bit
_stat32i64, _wstat32i64	Not affected by the macro definition	32-bit	64-bit
_stat64i32, _wstat64i32	Not affected by the macro definition	64-bit	32-bit

Generic-Text Routine Mappings

TCHAR.H routine	_UNICODE & _MBCS not defined	_MBCS defined	_UNICODE defined
_tstat	_stat	_stat	_wstat
_tstat64	_stat64	_stat64	_wstat64
_tstati64	_stati64	_stati64	_wstati64
_tstat32i64	_stat32i64	_stat32i64	_wstat32i64
_tstat64i32	_stat64i32	_stat64i32	_wstat64i32

The _stat structure, defined in SYS\STAT.H, includes the following fields.

st_gid
Numeric identifier of group that owns the file (UNIX-specific) This field will always be zero on Windows systems.A redirected file is classified as a Windows file.
st_atime
Time of last access of file.Valid on NTFS but not on FAT formatted disk drives.
st_ctime
Time of creation of file.Valid on NTFS but not on FAT formatted disk drives.
st_dev
Drive number of the disk containing the file (same as st_rdev).
st_ino
Number of the information node (the inode) for the file (UNIX-specific).On UNIX file systems, the inode describes the file date and time stamps, permissions, and content.When files are hard-linked to one another, they share the same inode.The inode, and therefore st_ino, has no meaning in the FAT, HPFS, or NTFS file systems.
st_mode
Bit mask for file-mode information.The _S_IFDIR bit is set if path specifies a directory; the _S_IFREG bit is set if path specifies an ordinary file or a device.User read/write bits are set according to the file's permission mode; user execute bits are set according to the filename extension.
st_mtime
Time of last modification of file.
st_nlink
Always 1 on non-NTFS file systems.
st_rdev
Drive number of the disk containing the file (same as st_dev).
st_size
Size of the file in bytes; a 64-bit integer for variations with the i64 suffix**.**
st_uid
Numeric identifier of user who owns file (UNIX-specific).This field will always be zero on Windows systems.A redirected file is classified as a Windows file.

If path refers to a device, the st_size, various time fields, st_dev, and st_rdev fields in the _stat structure are meaningless.Because STAT.H uses the _dev_t type that is defined in TYPES.H, you must include TYPES.H before STAT.H in your code.

Requisitos

Routine	Required header	Optional headers
_stat, _stat32, _stat64, _stati64, _stat32i64, _stat64i32	<sys/types.h> followed by <sys/stat.h>	<errno.h>
_wstat, _wstat32, _wstat64, _wstati64, _wstat32i64, _wstat64i32	<sys/types.h> followed by <sys/stat.h> or <wchar.h>	<errno.h>

For additional compatibility information, see Compatibility in the Introduction.

Ejemplo

// crt_stat.c
// This program uses the _stat function to
// report information about the file named crt_stat.c.#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <errno.h>

int main( void )
{
   struct _stat buf;
   int result;
   char timebuf[26];
   char* filename = "crt_stat.c";
   errno_t err;

   // Get data associated with "crt_stat.c": 
   result = _stat( filename, &buf );

   // Check if statistics are valid: 
   if( result != 0 )
   {
      perror( "Problem getting information" );
      switch (errno)
      {
         case ENOENT:
           printf("File %s not found.\n", filename);
           break;
         case EINVAL:
           printf("Invalid parameter to _stat.\n");
           break;
         default:
           /* Should never be reached.*/
           printf("Unexpected error in _stat.\n");
      }
   }
   else
   {
      // Output some of the statistics: 
      printf( "File size     : %ld\n", buf.st_size );
      printf( "Drive         : %c:\n", buf.st_dev + 'A' );
      err = ctime_s(timebuf, 26, &buf.st_mtime);
      if (err)
      {
         printf("Invalid arguments to ctime_s.");
         exit(1);
      }
      printf( "Time modified : %s", timebuf );
   }
}

File size     : 732
Drive         : C:
Time modified : Thu Feb 07 14:39:36 2002