What is the difference between clock_t, time_t and struct tm?

Question

What is the difference between clock_t, time_t and struct tm?

struct tm looks like this:

struct tm{
int tm_sec;
int tm_min;
int tm_hour;         


        

Answer 1

C just says that:

(C99, 7.23.1p3) "clock_t and time_t which are arithmetic types capable of representing times"

In the glibc, the type time_t is an alias to long.

In the GNU C library, time_t is equivalent to long int

from http://www.gnu.org/software/libc/manual/html_node/Simple-Calendar-Time.html