inet(3n)inet(3n)Name
inet_addr, inet_network, inet_ntoa, inet_makeaddr, inet_lnaof,
inet_netof - Internet address manipulation routines
Syntax
#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 and each interpret character strings representing numbers
expressed in the Internet standard “.” notation, returning numbers
suitable for use as Internet addresses and Internet network numbers,
respectively. The routine takes an Internet address and returns an
ASCII string representing the address in “.” notation. The routine
takes an Internet network number and a local network address and con‐
structs an Internet address from it. The routines and 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 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 right most two bytes of the network
address. This makes the three-part address format convenient for spec‐
ifying 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 speci‐
fying Class A network addresses as “net.host”.
When only one part is given, the value is stored directly in the net‐
work address without any byte rearrangement.
All numbers supplied as “parts” in a “.” notation may be decimal,
octal, or hexadecimal, as specified in the C language (i.e. a leading
0x or 0X implies hexadecimal; otherwise, a leading 0 implies octal;
otherwise, the number is interpreted as decimal).
Return Values
The value -1 is returned by and for malformed requests.
See Alsogethostent(3n), getnetent(3n), hosts(5), networks(5)inet(3n)