NAME

       inet_addr, inet_ntoa - IPv4 address manipulation

SYNOPSIS

       #include <arpa/inet.h>

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

DESCRIPTION

       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 reentrant. A function that is not required to be
       reentrant is not required to 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).

RETURN VALUE

       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.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

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

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       endhostent()  ,  endnetent()  ,  the  Base  Definitions  volume  of  IEEE Std 1003.1-2001,
       <arpa/inet.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  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 .