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 
       #include 
       #include 

       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);

DESCRIPTION
       inet_aton() converts the Internet host address cp from the standard numbers-and-dots nota-
       tion 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 nota-
       tion  into  binary data in network byte order.  If the input is invalid, INADDR_NONE (usu-
       ally -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       above;  it is obsolete because -1 is a valid address (255.255.255.255), and inet_aton pro-
       vides 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 subsequent calls will overwrite.

       The  inet_makeaddr() function makes an Internet host address in network byte order by com-
       bining 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 Significant 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), inet_ntop(3), inet_pton(3), hosts(5), networks(5)



BSD                                         2001-07-25                                    INET(3)