_vfprintf_p, _vfprintf_p_l, _vfwprintf_p, _vfwprintf_p_l

Write formatted output using a pointer to a list of arguments, with the ability to specify the order that arguments are used in the format string.

int _vfprintf_p(
   FILE *stream,
   const char *format,
   va_list argptr 
int _vfprintf_p_l(
   FILE *stream,
   const char *format,
   locale_t locale,
   va_list argptr 
int _vfwprintf_p(
   FILE *stream,
   const wchar_t *format,
   va_list argptr 
int _vfwprintf_p_l(
   FILE *stream,
   const wchar_t *format,
   locale_t locale,
   va_list argptr 


  • 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_p and _vfwprintf_p return the number of characters written, not including the terminating null character, or a negative value if an output error occurs.


Each of these functions takes a pointer to an argument list, then formats and writes the given data to stream. These functions differ from the _vfprint_s and _vfwprint_s versions only in that they support positional parameters. For more information, see printf_p Positional Parameters.

_vfwprintf_p is the wide-character version of _vprintf_p; the two functions behave identically if the stream is opened in ANSI mode. _vprintf_p 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 noteSecurity Note

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

If either stream or format is a null pointer, or if the format string contains invalid formatting characters, 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.

Generic-Text Routine Mappings

TCHAR.H routine

_UNICODE & _MBCS not defined

_MBCS defined

_UNICODE defined











Required header

Optional headers

_vfprintf_p, _vfprintf_p_l

<stdio.h> and <stdarg.h>


_vfwprintf_p, _vfwprintf_p_l

<stdio.h> or <wchar.h>, and <stdarg.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


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_copy, va_end, va_start

printf_p Positional Parameters

_fprintf_p, _fprintf_p_l, _fwprintf_p, _fwprintf_p_l

_vsprintf_p, _vsprintf_p_l, _vswprintf_p, _vswprintf_p_l

_sprintf_p, _sprintf_p_l, _swprintf_p, _swprintf_p_l