#include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h>
inet_aton(3) converts the Internet host address cp from the standard numbers-and-dots notation into binary data and stores it in the structure that inp points to. inet_aton(3) returns nonzero if the address is valid, zero if not.
The inet_addr(3) function converts the Internet host address cp from numbers-and-dots notation into binary data in network byte order. If the input is invalid, INADDR_NONE (usually -1) is returned. This is an obsolete interface to inet_aton, described immediately above; it is obsolete because -1 is a valid address (255.255.255.255), and inet_aton(3) provides a cleaner way to indicate error return.
The inet_network(3) function extracts the network number in host byte order from the address cp in numbers-and-dots notation. If the input is invalid, -1 is returned.
The inet_ntoa(3) function converts the Internet host address in given in network byte order to a string in standard numbers-and-dots notation. The string is returned in a statically allocated buffer, which subsequent calls will overwrite. ** Valgrind reports a memory leak when using this function. No solution has as of yet been found.
The inet_makeaddr(3) function makes an Internet host address in network byte order by combining the network number net with the local address host in network net, both in local host byte order.
The inet_lnaof(3) function returns the local host address part of the Internet address in. The local host address is returned in local host byte order.
The inet_netof(3) function returns the network number part of the Internet Address in. The network number is returned in local host byte order.
Note that on the i80x86 the host byte order is Least Significant Byte first, whereas the network byte order, as used on the Internet, is Most Significant Byte first.