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INET_ADDR(3P) POSIX Programmer's Manual INET_ADDR(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
inet_addr, inet_ntoa — IPv4 address manipulation
#include <arpa/inet.h>
in_addr_t inet_addr(const char *cp);
char *inet_ntoa(struct in_addr in);
The inet_addr() function shall convert the string pointed to by cp,
in the standard IPv4 dotted decimal notation, to an integer value
suitable for use as an Internet address.
The inet_ntoa() function shall convert the Internet host address
specified by in to a string in the Internet standard dot notation.
The inet_ntoa() function need not be thread-safe.
All Internet addresses shall be returned in network order (bytes
ordered from left to right).
Values specified using IPv4 dotted decimal notation take one of the
following forms:
a.b.c.d When four parts are specified, each shall be interpreted as
a byte of data and assigned, from left to right, to the
four bytes of an Internet address.
a.b.c When a three-part address is specified, the last part shall
be interpreted as a 16-bit quantity and placed in the
rightmost two bytes of the network address. This makes the
three-part address format convenient for specifying Class B
network addresses as "128.net.host".
a.b When a two-part address is supplied, the last part shall be
interpreted as a 24-bit quantity and placed in the
rightmost three bytes of the network address. This makes
the two-part address format convenient for specifying Class
A network addresses as "net.host".
a When only one part is given, the value shall be stored
directly in the network address without any byte
rearrangement.
All numbers supplied as parts in IPv4 dotted decimal notation may be
decimal, octal, or hexadecimal, as specified in the ISO C standard
(that is, a leading 0x or 0X implies hexadecimal; otherwise, a
leading '0' implies octal; otherwise, the number is interpreted as
decimal).
Upon successful completion, inet_addr() shall return the Internet
address. Otherwise, it shall return (in_addr_t)(−1).
The inet_ntoa() function shall return a pointer to the network
address in Internet standard dot notation.
No errors are defined.
The following sections are informative.
None.
The return value of inet_ntoa() may point to static data that may be
overwritten by subsequent calls to inet_ntoa().
None.
None.
endhostent(3p), endnetent(3p)
The Base Definitions volume of POSIX.1‐2008, arpa_inet.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 INET_ADDR(3P)
Pages that refer to this page: arpa_inet.h(0p), endservent(3p), freeaddrinfo(3p), inet_ntop(3p)
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