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INET_ADDR(3P)              POSIX Programmer's Manual             INET_ADDR(3P)

PROLOG
       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.
NAME
       inet_addr, inet_ntoa - IPv4 address manipulation
SYNOPSIS
       #include <arpa/inet.h>
       in_addr_t inet_addr(const char *cp);
       char *inet_ntoa(struct in_addr in);

DESCRIPTION
       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 speci-
       fied by in to a string in the Internet standard dot notation.
       The  inet_ntoa() function need not be reentrant. A function that is not
       required to be reentrant is not required to 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).
RETURN VALUE
       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.
ERRORS
       No errors are defined.
       The following sections are informative.
EXAMPLES
       None.
APPLICATION USAGE
       The return value of inet_ntoa() may point to static data  that  may  be
       overwritten by subsequent calls to inet_ntoa().
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       endhostent(),    endnetent(),    the   Base   Definitions   volume   of
       IEEE Std 1003.1-2001, <arpa/inet.h>
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open  Group.  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.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003                        INET_ADDR(3P)