INET(3N)                             BSD                              INET(3N)



NAME
     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>

     unsigned long inet_addr(cp)
     char *cp;

     unsigned long inet_network(cp)
     char *cp;

     char *inet_ntoa(in)
     struct in_addr in;

     struct in_addr inet_makeaddr(net, lna)
     int net, lna;

     int inet_lnaof(in)
     struct in_addr in;

     int inet_netof(in)
     struct in_addr in;

DESCRIPTION
     The routines inet_addr and inet_network each interpret character strings
     representing numbers expressed in the Internet standard dot (.)
     notation, returning numbers suitable for use as Internet addresses and
     Internet network numbers, respectively.  The routine inet_ntoa takes an
     Internet address and returns an ASCII string representing the address in
     "." notation.  The routine inet_makeaddr takes an Internet network number
     and a local network address and constructs an Internet address from it.
     The routines inet_netof and inet_lnaof break apart Internet host
     addresses, returning the network number and local network address part,
     respectively.

     All Internet address are returned in network order (bytes ordered from
     left to right).  All network numbers and local address parts are returned
     as machine format integer values.

INTERNET ADDRESSES
     Values specified by using the "." notation take one of the following
     forms:
          a.b.c.d
          a.b.c
          a.b
          a
     When four parts are specified, each is interpreted as a byte of data and
     assigned, from left to right, to the four bytes of an Internet address.
     Note that, when an Internet address is viewed as a 32-bit integer
     quantity on the VAX, the bytes referred to above appear as "d.c.b.a".
     That is, VAX bytes are ordered from right to left.

     When a three-part address is specified, the last part is 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".

     When a two-part address is supplied, the last part is interpreted as a
     24-bit quantity and placed in the right most three bytes of the network
     address.  This makes the two-part address format convenient for
     specifying Class A network addresses as "net.host".

     When only one part is given, the value is stored directly in the network
     address without any byte rearrangement.

     All numbers supplied as "parts" in a "." notation can be decimal, octal,
     or hexadecimal, as specified in the C language (that is, a leading 0x or
     0X implies hexadecimal; otherwise, a leading 0 implies octal; otherwise,
     the number is interpreted as decimal).

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

DIAGNOSTICS
     The value -1 is returned by inet_addr and inet_network for malformed
     requests.

BUGS
     The problem of host byte ordering versus network byte ordering is
     confusing.  A simple way to specify Class C network addresses in a manner
     similar to that for Class B and Class A is needed.  The string returned
     by inet_ntoa resides in a static memory area.
     inet_addr should return a struct in_addr.