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.\" $OpenBSD: htonl.3,v 1.3 2014/09/04 13:51:54 millert Exp $
.\"
.\" Copyright (c) 1983, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd $Mdocdate: September 4 2014 $
.Dt HTONL 3
.Os
.Sh NAME
.Nm htonl ,
.Nm htons ,
.Nm ntohl ,
.Nm ntohs
.Nd convert values between host and network byte orderings
.Sh SYNOPSIS
.In arpa/inet.h
.Ft uint32_t
.Fn htonl "uint32_t host32"
.Ft uint16_t
.Fn htons "uint16_t host16"
.Ft uint32_t
.Fn ntohl "uint32_t net32"
.Ft uint16_t
.Fn ntohs "uint16_t net16"
.Sh DESCRIPTION
These routines convert 16 and 32-bit quantities between different
byte orderings.
.Pp
The
.Fn htonl
and
.Fn htons
functions convert quantities from host to network byte order while the
.Fn ntohl
and
.Fn ntohs
functions convert in the other direction.
.Pp
The last letter
.Pf ( Sq s
or
.Sq l )
is a mnemonic
for the traditional names for such quantities,
.Li short
and
.Li long ,
respectively.
Today, the C concept of
.Li short
and
.Li long
integers need not coincide with this traditional misunderstanding.
On machines which have a byte order which is the same as the network
order, routines are defined as null macros.
.Pp
These routines are most often used in conjunction with Internet
addresses and ports as returned by
.Xr gethostbyname 3
and
.Xr getservent 3 .
.Sh SEE ALSO
.Xr gethostbyname 3 ,
.Xr getservent 3
.Sh STANDARDS
The
.Fn htonl ,
.Fn htons ,
.Fn ntohl ,
and
.Fn ntohs
functions conform to
.St -p1003.1 .
.Sh HISTORY
These functions appeared in
.Bx 4.2 .
.Sh BUGS
On the vax, alpha, amd64, i386, and some mips and arm architectures,
bytes are handled backwards from most everyone else in the world.
This is not expected to be fixed in the near future.
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