vfprintf, _vfprintf_l, vfwprintf, _vfwprintf_l

Write formatted output using a pointer to a list of arguments. More secure versions of these functions exist; see vfprintf_s, _vfprintf_s_l, vfwprintf_s, _vfwprintf_s_l.

int vfprintf(
   FILE *stream,
   const char *format,
   va_list argptr 
);
int _vfprintf_l(
   FILE *stream,
   const char *format,
   locale_t locale,
   va_list argptr 
);
int vfwprintf(
   FILE *stream,
   const wchar_t *format,
   va_list argptr 
);
int _vfwprintf_l(
   FILE *stream,
   const wchar_t *format,
   locale_t locale,
   va_list argptr 
);

Parameters

• stream
  Pointer to FILE structure.

• format
  Format specification.

• argptr
  Pointer to list of arguments.

• locale
  The locale to use.

For more information, see Format Specifications.

Return Value

vfprintf and vfwprintf return the number of characters written, not including the terminating null character, or a negative value if an output error occurs. If either stream or format is a null pointer, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, the functions return -1 and set errno to EINVAL.

For information on these and other error codes, see _doserrno, errno, _sys_errlist, and _sys_nerr.

Remarks

Each of these functions takes a pointer to an argument list, then formats and writes the given data to stream.

vfwprintf is the wide-character version of vfprintf; the two functions behave identically if the stream is opened in ANSI mode. vfprintf doesn't currently support output into a UNICODE stream.

The versions of these functions with the _l suffix are identical except that they use the locale parameter passed in instead of the current thread locale.

Security Note
Ensure that format is not a user-defined string. For more information, see Avoiding Buffer Overruns.

Generic-Text Routine Mappings

TCHAR.H routine	_UNICODE & _MBCS not defined	_MBCS defined	_UNICODE defined
_vftprintf	vfprintf	vfprintf	vfwprintf
_vftprintf_l	_vfprintf_l	_vfprintf_l	_vfwprintf_l

Requirements

Routine	Required header	Optional headers
vfprintf, _vfprintf_l	<stdio.h> and <stdarg.h>	<varargs.h>*
vfwprintf, _vfwprintf_l	<stdio.h> or <wchar.h>, and <stdarg.h>	<varargs.h>*

* Required for UNIX V compatibility.

For additional compatibility information, see Compatibility in the Introduction.

.NET Framework Equivalent

Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.

See Also

Reference

Stream I/O

vprintf Functions

fprintf, _fprintf_l, fwprintf, _fwprintf_l

printf, _printf_l, wprintf, _wprintf_l

sprintf, _sprintf_l, swprintf, _swprintf_l, __swprintf_l

va_arg, va_end, va_start