#include <time.h>time_t time(time_t *time);
The time( ) function returns the current calendar time of the system. If the system has no time, –1 is returned.
The time( ) function can be called either with a null pointer or with a pointer to a variable of type time_t. If the latter is used, the variable will also be assigned the calendar time.
Related functions are localtime( ), gmtime( ), strftime( ), and ctime( ).