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_creat, _wcreat

Creates a new file. _creat and _wcreat have been deprecated; use _sopen_s, _wsopen_s instead.

int _creat( 
   const char *filename,
   int pmode 
);
int _wcreat( 
   const wchar_t *filename,
   int pmode 
);

filename

Name of new file.

pmode

Permission setting.

These functions, if successful, return a file descriptor to the created file. Otherwise, the functions return –1 and set errno as shown in the following table.

errno setting

Description

EACCES

filename specifies an existing read-only file or specifies a directory instead of a file.

EMFILE

No more file descriptors are available.

ENOENT

Specified file could not be found.

If filename is NULL, these functions invoke the invalid parameter handler, as described in Parameter Validation. If execution is allowed to continue, these functions set errno to EINVAL and return -1.

For more information about these and other return codes, see _doserrno, errno, _sys_errlist, and _sys_nerr.

The _creat function creates a new file or opens and truncates an existing one. _wcreat is a wide-character version of _creat; the filename argument to _wcreat is a wide-character string. _wcreat and _creat behave identically otherwise.

Generic-Text Routine Mappings

Tchar.h routine

_UNICODE and _MBCS not defined

_MBCS defined

_UNICODE defined

_tcreat

_creat

_creat

_wcreat

If the file specified by filename does not exist, a new file is created with the given permission setting and is opened for writing. If the file already exists and its permission setting allows writing, _creat truncates the file to length 0, destroying the previous contents, and opens it for writing. The permission setting, pmode, applies to newly created files only. The new file receives the specified permission setting after it is closed for the first time. The integer expression pmode contains one or both of the manifest constants _S_IWRITE and _S_IREAD, defined in SYS\Stat.h. When both constants are given, they are joined with the bitwise OR operator ( | ). The pmode parameter is set to one of the following values.

Value

Definition

_S_IWRITE

Writing permitted.

_S_IREAD

Reading permitted.

_S_IREAD | _S_IWRITE

Reading and writing permitted.

If write permission is not given, the file is read-only. All files are always readable; it is impossible to give write-only permission. The modes _S_IWRITE and _S_IREAD| _S_IWRITE are then equivalent. Files opened using _creat are always opened in compatibility mode (see _sopen) with _SH_DENYNO.

_creat applies the current file-permission mask to pmode before setting the permissions (see _umask). _creat is provided primarily for compatibility with previous libraries. A call to _open with _O_CREAT and _O_TRUNC in the oflag parameter is equivalent to _creat and is preferable for new code.

Routine

Required header

Optional header

_creat

<io.h>

<sys/types.h>, <sys/stat.h>, <errno.h>

_wcreat

<io.h> or <wchar.h>

<sys/types.h>, <sys/stat.h>, <errno.h>

For more compatibility information, see Compatibility in the Introduction.

// crt_creat.c
// compile with: /W3
// This program uses _creat to create
// the file (or truncate the existing file)
// named data and open it for writing.

#include <sys/types.h>
#include <sys/stat.h>
#include <io.h>
#include <stdio.h>
#include <stdlib.h>

int main( void )
{
   int fh;

   fh = _creat( "data", _S_IREAD | _S_IWRITE ); // C4996
   // Note: _creat is deprecated; use _sopen_s instead
   if( fh == -1 )
      perror( "Couldn't create data file" );
   else
   {
      printf( "Created data file.\n" );
      _close( fh );
   }
}
Created data file.

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