printf-printf-l-wprintf-wprintf-l.md

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Learn more about: printf, _printf_l, wprintf, _wprintf_l	printf, _printf_l, wprintf, _wprintf_l	3/9/2021	_printf_l wprintf _wprintf_l printf	msvcrt.dll msvcr80.dll msvcr90.dll msvcr100.dll msvcr100_clr0400.dll msvcr110.dll msvcr110_clr0400.dll msvcr120.dll msvcr120_clr0400.dll ucrtbase.dll	DLLExport	apiref	printf _tprintf wprintf	printf function printf_l function tprintf_l function tprintf function _printf_l function wprintf function writing to console wprintf_l function _tprintf_l function _wprintf_l function _tprintf function printf function, format specification fields printf function, using formatted text [C++]

printf, _printf_l, wprintf, _wprintf_l

Prints formatted output to the standard output stream. More secure versions of these functions are available; see printf_s, _printf_s_l, wprintf_s, _wprintf_s_l.

Syntax

intprintf( constchar*format [, argument]... ); int_printf_l( constchar*format, _locale_tlocale [, argument]... ); intwprintf( constwchar_t*format [, argument]... ); int_wprintf_l( constwchar_t*format, _locale_tlocale [, 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. If format is NULL, the invalid parameter handler is invoked, as described in Parameter validation. If execution is allowed to continue, the function returns -1 and sets errno to EINVAL. If EOF (0xFFFF) is encountered in argument, the function returns -1.

For information on errno and error codes, see errno, _doserrno, _sys_errlist, and _sys_nerr.

Remarks

The printf 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. printf and fprintf behave identically except that printf writes output to stdout rather than to a destination of type FILE.

wprintf is a wide-character version of printf; format is a wide-character string. wprintf and printf behave identically if the stream is opened in ANSI mode. printf 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.

The format argument consists of ordinary characters, escape sequences, and (if arguments follow format) format specifications. The ordinary characters and escape sequences are copied to stdout in order of their appearance. For example, the line:

printf("Line one\n\t\tLine two\n");

produces the output:

Line one Line two 

Format specifications always begin with a percent sign (%) and are read left to right. When printf encounters the first format specification (if any), it converts the value of the first argument after format and outputs it accordingly. The second format specification causes the second argument to be converted and output, and so on. If there are more arguments than there are format specifications, the extra arguments are ignored. The results are undefined if there aren't enough arguments for all the format specifications.

Important

Ensure that format is not a user-defined string.

Generic-text routine mappings

Tchar.h routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
_tprintf	printf	printf	wprintf
_tprintf_l	_printf_l	_printf_l	_wprintf_l

Requirements

Routine	Required header
printf, _printf_l	<stdio.h>
wprintf, _wprintf_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.c// This program uses the printf and wprintf functions// to produce formatted output.#include<stdio.h>intmain( void ) { charch='h', *string="computer"; wchar_twch=L'w', *wstring=L"Unicode"; intcount=-9234; doublefp=251.7366; // Display integersprintf( "Integer formats:\n"" Decimal: %d Justified: %.6d ""Unsigned: %u\n", count, count, count, count ); // Display decimalsprintf( "Decimal %d as:\n Hex: %Xh ""C hex: 0x%x Octal: %o\n", count, count, count, count ); // Display in different radixesprintf( "Digits 10 equal:\n Hex: %i ""Octal: %i Decimal: %i\n", 0x10, 010, 10 ); // Display charactersprintf("Characters in field (1):\n""%10c%5hc%5C%5lc\n", ch, ch, wch, wch); wprintf(L"Characters in field (2):\n"L"%10C%5hc%5c%5lc\n", ch, ch, wch, wch); // Display stringsprintf("Strings in field (1):\n%25s\n""%25.4hs\n %S%25.3ls\n", string, string, wstring, wstring); wprintf(L"Strings in field (2):\n%25S\n"L"%25.4hs\n %s%25.3ls\n", string, string, wstring, wstring); // Display real numbersprintf("Real numbers:\n %f %.2f %e %E\n", fp, fp, fp, fp ); // Display pointerprintf( "\nAddress as: %p\n", &count); }

Sample output

Integer formats: Decimal: -9234 Justified: -009234 Unsigned: 4294958062 Decimal -9234 as: Hex: FFFFDBEEh C hex: 0xffffdbee Octal: 37777755756 Digits 10 equal: Hex: 16 Octal: 8 Decimal: 10 Characters in field (1): h h w w Characters in field (2): h h w w Strings in field (1): computer comp Unicode Uni Strings in field (2): computer comp Unicode Uni Real numbers: 251.736600 251.74 2.517366e+002 2.517366E+002 Address as: 0012FF3C 

See also

Format specification syntax: printf and wprintf functions
Math and floating-point support
Stream I/O
Locale
fopen, _wfopen
_fprintf_p, _fprintf_p_l, _fwprintf_p, _fwprintf_p_l
scanf, _scanf_l, wscanf, _wscanf_l
sprintf, _sprintf_l, swprintf, _swprintf_l, __swprintf_l
vprintf functions
_set_output_format