vfprintf, _vfprintf_l, vfwprintf, _vfwprintf_l


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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   


Pointer to FILE structure.

Format specification.

Pointer to list of arguments.

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.


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.


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


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

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