Edit

Share via

_vscprintf, _vscprintf_l, _vscwprintf, _vscwprintf_l

  • Article

Returns the number of characters in the formatted string using a pointer to a list of arguments.

Syntax

int _vscprintf(
   const char *format,
   va_list argptr
);
int _vscprintf_l(
   const char *format,
   _locale_t locale,
   va_list argptr
);
int _vscwprintf(
   const wchar_t *format,
   va_list argptr
);
int _vscwprintf_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 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 performs the same function for wide characters.

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.

Remarks

Each argument (if any) is converted according to the corresponding format specification in format. The format consists of ordinary characters and has the same form and function as the format argument for printf.

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 _vscprintf _vscprintf _vscwprintf
_vsctprintf_l _vscprintf_l _vscprintf_l _vscwprintf_l

Requirements

Routine Required header
_vscprintf, _vscprintf_l <stdio.h>
_vscwprintf, _vscwprintf_l <stdio.h> or <wchar.h>

For more compatibility information, see Compatibility.

Example

See the example for vsprintf.

See also

Stream I/O
fprintf, _fprintf_l, fwprintf, _fwprintf_l
printf, _printf_l, wprintf, _wprintf_l
scanf, _scanf_l, wscanf, _wscanf_l
sscanf, _sscanf_l, swscanf, _swscanf_l
vprintf functions