inet.3n (2010 09)

inet(3N) inet(3N)

specifying Class A network addresses as in

net.host.

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

rangement.

All numbers supplied as parts in dot notation can be decimal, octal, or hexadecimal, as speciﬁed in the C

language (i.e., a leading 0x or 0X implies hexadecimal; a leading 0 implies octal; otherwise, the number is

interpreted as decimal).

In a multithreaded application, inet_ntoa() uses thread-speciﬁc storage that is re-used in each call.

The return value, the character string, should be unique for each thread and should be saved, if desired,

before the thread makes the next

inet_ntoa()

call.

Obsolescent Interfaces

The following reentrant interface has been moved from

libc to libd4r.

int inet_ntoa_r(struct in_addr

in, char *buffer

, int buﬂen);

It is included to support existing applications and may be removed in a future release. New mul-

tithreaded applications should use the regular API (those without the

_r sufﬁx.)

The reentrant interface functions the same as the regular interface without the

_r sufﬁx. However,

inet_ntoa_r()

expects to be passed the address of a character buffer and will store the result at the

supplied location. If the buffer is of insufﬁcient length,

-1 is returned. If the operation is successful, the

length of the result string (not including the terminating null character) is returned.

RETURN VALUE

The routines return values as described in the DESCRIPTION section.

inet_addr() and

inet_network() return -1

(INADDR_NONE) for malformed requests.

WARNINGS

The return value from the

inet_addr() function cannot distinguish between a failure (-1) and a local

broadcast address (255.255.255.255). This can be handled by using the

inet_pton() function instead

of the

inet_addr() function.

AUTHOR

The

inet routines were developed by the University of California, Berkeley.