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NAME

       inet_aton,    inet_addr,    inet_network,   inet_ntoa,   inet_makeaddr,
       inet_lnaof, inet_netof - Internet address manipulation routines

SYNOPSIS

       #include <sys/socket.h>
       #include <netinet/in.h>
       #include <arpa/inet.h>

       int inet_aton(const char *cp, struct in_addr *inp);

       in_addr_t inet_addr(const char *cp);

       in_addr_t inet_network(const char *cp);

       char *inet_ntoa(struct in_addr in);

       struct in_addr inet_makeaddr(int net, int host);

       in_addr_t inet_lnaof(struct in_addr in);

       in_addr_t inet_netof(struct in_addr in);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       inet_aton(), inet_ntoa(): _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       inet_aton() converts the Internet host address  cp  from  the  standard
       numbers-and-dots  notation  into  binary  data  and  stores  it  in the
       structure that inp points  to.   inet_aton()  returns  nonzero  if  the
       address is valid, zero if not.

       The  inet_addr()  function  converts  the Internet host address cp from
       numbers-and-dots notation into binary data in network byte  order.   If
       the input is invalid, INADDR_NONE (usually -1) is returned.  This is an
       obsolete interface to inet_aton(), described immediately above;  it  is
       obsolete   because   -1  is  a  valid  address  (255.255.255.255),  and
       inet_aton() provides a cleaner way to indicate error return.

       The inet_network() function  extracts  a  number  in  host  byte  order
       suitable  for  use as an Internet address from cp, which is a string in
       numbers-and-dots notation.  If the input is invalid, -1 is returned.

       The inet_ntoa() function converts the Internet host address in given in
       network  byte  order to a string in standard numbers-and-dots notation.
       The  string  is  returned  in  a  statically  allocated  buffer,  which
       subsequent calls will overwrite.

       The  inet_makeaddr() function makes an Internet host address in network
       byte order by combining the network number net with the  local  address
       host in network net, both in local host byte order.

       The  inet_lnaof()  function  returns the local host address part of the
       Internet address in.  The local host address is returned in local  host
       byte order.

       The  inet_netof()  function  returns  the  network  number  part of the
       Internet Address in.  The network number is returned in local host byte
       order.

       The   structure   in_addr  as  used  in  inet_ntoa(),  inet_makeaddr(),
       inet_lnaof() and inet_netof() is defined in <netinet/in.h> as:

           typedef uint32_t in_addr_t;

           struct in_addr {
               in_addr_t s_addr;
           };

       Note that on the i386 the host byte order  is  Least  Significant  Byte
       first  (little  endian), whereas the network byte order, as used on the
       Internet, is Most Significant Byte first (big endian).

CONFORMING TO

       4.3BSD.  inet_addr(), inet_aton(), and  inet_ntoa()  are  specified  in
       POSIX.1-2001.

NOTES

       When  you  using numbers-and-dots notation for addresses, be aware that
       each number will be interpreted as octal if preceded  by  a  0  and  as
       hexadecimal      if      preceded      by     0x.      For     example,
       inet_aton("226.000.000.037",  &t)  will  interpret   the   address   as
       226.0.0.31 and not 226.0.0.37.

SEE ALSO

       gethostbyname(3),  getnetent(3),  inet_ntop(3), inet_pton(3), hosts(5),
       networks(5)

COLOPHON

       This page is part of release 2.77 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.