INET(3)             Linux Programmer's Manual             INET(3)

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);

       unsigned long int inet_addr(const char *cp);

       unsigned long int inet_network(const char *cp);

       char *inet_ntoa(struct in_addr in);

       struct in_addr inet_makeaddr(int net, int host);

       unsigned long int inet_lnaof(struct in_addr in);

       unsigned long int inet_netof(struct in_addr in);

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       interface to inet_aton, described immediately above; it is
       obsolete  because -1 is a valid address (255.255.255.255),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 the network number in
       host byte order from the address  cp  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  subse-
       quent 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_lnoaf() and inet_netof() is defined
       in netinet/in.h as:

              struct in_addr {
                      unsigned long int s_addr;
              }

       Note that on the i80x86 the host byte order is Least  Sig-
       nificant  Byte  first,  whereas the network byte order, as
       used on the Internet, is Most Significant Byte first.

CONFORMING TO
       BSD 4.3

SEE ALSO
       gethostbyname(3), getnetent(3), hosts(5), networks(5)

BSD                     September 3, 1995                       1