#include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h>
unsigned long inet_addr(cp) const char *cp;
unsigned long inet_network(cp) const char *cp;
int inet_aton(cp, val) const char *cp; struct in_addr *val;
char *inet_ntoa(in) struct in_addr in;
struct in_addr inet_makeaddr(net, lna) unsigned long net, lna;
unsigned long inet_lnaof(in) struct in_addr in;
unsigned long inet_netof(in) struct in_addr in;
The routine inet_ntoa takes an Internet address and returns an ASCII string representing the address in dot 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 addresses 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.
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.
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 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 ``dot'' notation may 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).