_vsnprintf sends data to the memory pointed to by buffer.

#include <stdio.h>
#include <stdarg.h>

int _vsnprintf(char *buffer, size_t size, const char *format, va_list ap);
int _vsnprintf_s(char *buffer, size_t size, size_t count, const char *format, va_list ap);

#include <wchar.h>
#include <stdarg.h>

int _vsnwprintf(wchar_t *buffer, size_t size, const wchar_t *format, va_list ap);
int _vsnwprintf_s(wchar_t *buffer, size_t size, size_t count, const wchar_t *format, va_list ap);

Parameters

buffer

Storage location for output.

size

The maximum number of characters to be stored in buffer.

count

Maximum number of characters to write (not including the terminating null), or _TRUNCATE.

format

Formatted string. This parameter has the same form and function as in printf.

ap

Pointer to list of arguments. This parameter has type va_list and points to a list of arguments that are converted and output according to the corresponding format specifications in format.

Remarks

These functions are similar to their counterparts vsnprintf and vsnprintf_s. _vsnprintf is identical to vsnprintf. _vsnprintf_s is similar to vsnprintf_s but takes an additional argument count to determine the number of characters to write to the buffer (vsnprintf_s always trancates the output to fit the buffer).

_vsnwpprintf and _vsnwprintf_s are wide-character versions of _vsnprintf and _vsnprintf_s respectively.

Return Values

The number of characters written, not counting the terminating null character.

Success.

A negative value if an output error occurs.

Failure.

Generic Text Routines

Requirements