in_addr v.s. in_addr_t

There are lots function/macros designed to convert them :



in_addr_t      inet_addr(const char *cp);
in_addr_t      inet_lnaof(struct in_addr in);
struct in_addr inet_makeaddr(in_addr_t net, in_addr_t lna);
in_addr_t      inet_netof(struct in_addr in);
in_addr_t      inet_network(const char *cp);
char          *inet_ntoa(struct in_addr in);

In fact, both in_addr_t, in_addr is defined in netinet/in.h :

#ifndef _IN_ADDR_T

#define _IN_ADDR_T

typedef __uint32_t in_addr_t;

#endif

struct in_addr {

  in_addr_t s_addr;

};

Struct in_addr contain/hide detail of IP address, so if you need to record IP inside your program, use struct in_addr maybe a better idea then in_addr_t.







Reference : http://pubs.opengroup.org/onlinepubs/7908799/xns/arpainet.h.html