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_inp, _inpw, _inpd

Inputs a byte (_inp), a word (_inpw), or a double word (_inpd) from a port.

int _inp(  
   unsigned short port  
unsigned short _inpw(  
   unsigned short port  
unsigned long _inpd(  
   unsigned short port  


  • port
    I/O port number.

Return Value

The functions return the byte, word, or double word read from port. There is no error return.


The _inp, _inpw, and _inpd functions read a byte, a word, and a double word, respectively, from the specified input port. The input value can be any unsigned short integer in the range 0 – 65,535.

Because these functions read directly from an I/O port, they might not be used in user code in Windows NT, Windows 2000, Windows XP, and Windows Server 2003. For information about using I/O ports in these operating systems, use the Win32 Communications API.



Required header







For more compatibility information, see Compatibility in the Introduction.


All versions of the C run-time libraries.

.NET Framework Equivalent

Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.

See Also


Console and Port I/O

_outp, _outpw, _outpd