outp-outpw-outpd.md

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outp, outpw, _outp, _outpw, _outpd	Describes the obsolete and removed outp, outpw, _outp, _outpw, and _outpd functions of the Microsoft C runtime library (CRT).	12/09/2019	_outpd _outp _outpw outp outpw	msvcrt.dll msvcr100.dll msvcr120.dll msvcr90.dll msvcr110_clr0400.dll msvcr110.dll msvcr80.dll	DLLExport	apiref	_outpw _outpd _outp outp outpw outpd	outpw function words _outpd function outpd function outp function ports, writing bytes at bytes, writing to ports words, writing to ports double words double words, writing to ports _outpw function _outp function	c200fe22-41f6-46fd-b0be-ebb805b35181

outp, outpw, _outp, _outpw, _outpd

Outputs, at a port, a byte (outp, _outp), a word (outpw, _outpw), or a double word (_outpd).

Important

These functions are obsolete. Beginning in Visual Studio 2015, they are not available in the CRT.
This API cannot be used in applications that execute in the Windows Runtime. For more information, see CRT functions not supported in Universal Windows Platform apps.

Syntax

int _outp(
   unsigned short port,
   int data_byte
);
unsigned short _outpw(
   unsigned short port,
   unsigned short data_word
);
unsigned long _outpd(
   unsigned short port,
   unsigned long data_word
);

Parameters

port
Port number.

data_byte, data_word
Output values.

Return value

The functions return the data output. There's no error return.

Remarks

The _outp, _outpw, and _outpd functions write a byte, a word, and a double word, respectively, to the specified output port. The port argument can be any unsigned integer in the range 0 - 65,535. data_byte can be any integer in the range 0 - 255. data_word can be any value in the range of an integer, an unsigned short integer, and an unsigned long integer, respectively.

Because these functions write directly to an I/O port, they can't be used in user-mode Windows code.

For information about using I/O ports in the Windows operating system, see Serial communications.

The outp and outpw names are older, deprecated names for the _outp and _outpw functions. For more information, see POSIX function names.

Requirements

Routine	Required header
_outp	<conio.h>
_outpw	<conio.h>
_outpd	<conio.h>

For more compatibility information, see Compatibility.

Libraries

All versions of the C run-time libraries.

See also

Console and port I/O
inp, inpw, _inp, _inpw, _inpd