This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       The  return  value of inet_ntoa() may point to static data that may be overwritten by subsequent calls to
       inet_ntoa().

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 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 .

       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                                   2017                                     INET_ADDR(3POSIX)

       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).

       No errors are defined.

       Thefollowingsectionsareinformative.

       None.

       None.

       inet_addr, inet_ntoa — IPv4 address manipulation

       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.

       None.

       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.

endhostent(), endnetent()

       The Base Definitions volume of POSIX.1‐2017, <arpa_inet.h>

       #include <arpa/inet.h>

       in_addr_t inet_addr(const char *cp);
       char *inet_ntoa(struct in_addr in);