Write formatted output using a pointer to a list of arguments.
int _vsnprintf( char *buffer, size_t count, const char *format, va_list argptr );
int _vsnwprintf( wchar_t *buffer, size_t count, const wchar_t *format, va_list argptr );
| Routine | Required Header | Optional Headers | Compatibility |
| _vsnprintf | <stdio.h> and <stdarg.h> | <varargs.h>1 | Win 95, Win NT |
| _vsnwprintf | <stdio.h> or <wchar.h>, and <stdarg.h> | <varargs.h>1 | Win 95, Win NT |
1 Required for UNIX V compatibility.
For additional compatibility information, see Compatibility in the Introduction.
Libraries
| LIBC.LIB | Single thread static library, retail version |
| LIBCMT.LIB | Multithread static library, retail version |
| MSVCRT.LIB | Import library for MSVCRT.DLL, retail version |
Return Value
_vsnprintf and _vsnwprintf return the number of characters written, not including the terminating null character, or a negative value if an output error occurs. For _vsnprintf, if the number of bytes to write exceeds buffer, then count bytes are written and –1 is returned.
Parameters
buffer
Storage location for output
count
Maximum number of characters to write
format
Format specification
argptr
Pointer to list of arguments
Remarks
Each of these functions takes a pointer to an argument list, then formats and writes the given data to the memory pointed to by buffer.
Generic-Text Routine Mappings
| TCHAR.H Routine | _UNICODE & _MBCS Not Defined | _MBCS Defined | _UNICODE Defined |
| _vsntprintf | _vsnprintf | _vsnprintf | _vsnwprintf |