_vscprintf_p, _vscprintf_p_l, _vscwprintf_p, _vscwprintf_p_l

Returns the number of characters in the formatted string using a pointer to a list of arguments, with the ability to specify the order in which the arguments are used.

Syntax

int _vscprintf_p(
   const char *format,
   va_list argptr
);
int _vscprintf_p_l(
   const char *format,
   _locale_t locale,
   va_list argptr
);
int _vscwprintf_p (
   const wchar_t *format,
   va_list argptr
);
int _vscwprintf_p_l(
   const wchar_t *format,
   _locale_t locale,
   va_list argptr
);

Parameters

format
Format-control string.

argptr
Pointer to list of arguments.

locale
The locale to use.

For more information, see Format specification syntax.

Return value

_vscprintf_p returns the number of characters that would be generated if the string pointed to by the list of arguments was printed or sent to a file or buffer using the specified formatting codes. The value returned doesn't include the terminating null character. _vscwprintf_p performs the same function for wide characters.

Remarks

These functions differ from _vscprintf and _vscwprintf only in that they support the ability to specify the order in which the arguments are used. For more information, see printf_p Positional Parameters.

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.

If 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.

Important

Ensure that if format is a user-defined string, it is null terminated and has the correct number and type of parameters. For more information, see Avoiding buffer overruns. Starting in Windows 10 version 2004 (build 19041), the printf family of functions prints exactly representable floating point numbers according to the IEEE 754 rules for rounding. In previous versions of Windows, exactly representable floating point numbers ending in '5' would always round up. IEEE 754 states that they must round to the closest even digit (also known as "Banker's Rounding"). For example, both printf("%1.0f", 1.5) and printf("%1.0f", 2.5) should round to 2. Previously, 1.5 would round to 2 and 2.5 would round to 3. This change only affects exactly representable numbers. For example, 2.35 (which, when represented in memory, is closer to 2.35000000000000008) continues to round up to 2.4. Rounding done by these functions now also respects the floating point rounding mode set by fesetround. Previously, rounding always chose FE_TONEAREST behavior. This change only affects programs built using Visual Studio 2019 version 16.2 and later. To use the legacy floating point rounding behavior, link with 'legacy_stdio_float_rounding.obj`.

Generic-text routine mappings

TCHAR.H routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
_vsctprintf_p	_vscprintf_p	_vscprintf_p	_vscwprintf_p
_vsctprintf_p_l	_vscprintf_p_l	_vscprintf_p_l	_vscwprintf_p_l

Requirements

Routine	Required header
_vscprintf_p, _vscprintf_p_l	<stdio.h>
_vscwprintf_p, _vscwprintf_p_l	<stdio.h> or <wchar.h>

For more compatibility information, see Compatibility.

Example

See the example for vsprintf.

See also

vprintf functions
_scprintf_p, _scprintf_p_l, _scwprintf_p, _scwprintf_p_l
_vscprintf, _vscprintf_l, _vscwprintf, _vscwprintf_l