_printf_p, _printf_p_l, _wprintf_p, _wprintf_p_l

Prints formatted output to the standard output stream, and enables specification of the order in which parameters are used in the format string.

Syntax

int _printf_p(
   const char *format [,
   argument]...
);
int _printf_p_l(
   const char *format,
   _locale_t locale [,
   argument]...
);
int _wprintf_p(
   const wchar_t *format [,
   argument]...
);
int _wprintf_p_l(
   const wchar_t *format,
   _locale_t locale [,
   argument]...
);

Parameters

format
Format control.

argument
Optional arguments.

locale
The locale to use.

Return value

Returns the number of characters printed or a negative value if an error occurs.

Remarks

The _printf_p function formats and prints a series of characters and values to the standard output stream, stdout. If arguments follow the format string, the format string must contain specifications that determine the output format for the arguments (see printf_p Positional Parameters).

The difference between _printf_p and printf_s is that _printf_p supports positional parameters, which allows specifying the order in which the arguments are used in the format string. For more information, see printf_p Positional Parameters.

_wprintf_p is the wide-character version of _printf_p; they behave identically if the stream is opened in ANSI mode. _printf_p 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.

Important

Ensure that format is not a user-defined string.

If format or argument are NULL, or of the format string contains invalid formatting characters, _printf_p and _wprintf_p functions invoke an invalid parameter handler, as described in Parameter validation. If execution is allowed to continue, the function returns -1 and sets errno to EINVAL.

Generic-text routine mappings

Tchar.h routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
_tprintf_p	_printf_p	_printf_p	_wprintf_p
_tprintf_p_l	_printf_p_l	_printf_p_l	_wprintf_p_l

Requirements

Routine	Required header
_printf_p, _printf_p_l	<stdio.h>
_wprintf_p, _wprintf_p_l	<stdio.h> or <wchar.h>

The console isn't supported in Universal Windows Platform (UWP) apps. The standard stream handles that are associated with the console, stdin, stdout, and stderr, must be redirected before C run-time functions can use them in UWP apps. For more compatibility information, see Compatibility.

Important

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.

Example

// crt_printf_p.c
// This program uses the _printf_p and _wprintf_p
// functions to choose the order in which parameters
// are used.

#include <stdio.h>

int main( void )
{
   // Positional arguments
   _printf_p( "Specifying the order: %2$s %3$s %1$s %4$s %5$s.\n",
              "little", "I'm", "a", "tea", "pot");

   // Resume arguments
   _wprintf_p( L"Reusing arguments: %1$d %1$d %1$d %1$d\n", 10);

   // Width argument
   _printf_p("Width specifiers: %1$*2$s", "Hello\n", 10);
}

Specifying the order: I'm a little tea pot.
Reusing arguments: 10 10 10 10
Width specifiers:     Hello

See also

Math and floating-point support
Stream I/O
Locale
fopen, _wfopen
_fprintf_p, _fprintf_p_l, _fwprintf_p, _fwprintf_p_l
fprintf, _fprintf_l, fwprintf, _fwprintf_l
fprintf_s, _fprintf_s_l, fwprintf_s, _fwprintf_s_l
scanf, _scanf_l, wscanf, _wscanf_l
scanf_s, _scanf_s_l, wscanf_s, _wscanf_s_l
_sprintf_p, _sprintf_p_l, _swprintf_p, _swprintf_p_l
sprintf, _sprintf_l, swprintf, _swprintf_l, __swprintf_l
sprintf_s, _sprintf_s_l, swprintf_s, _swprintf_s_l
vprintf functions