time() - get time of day
time_t time (time_t *tloc)
The time(2) function returns the value of time in seconds since 0 hours, 0 minutes, 0 seconds, January 1, 1970, Coordinated Universal Time.
A copy of the time value may be saved to the area indicated by the pointer tloc. If tloc is a NULL pointer, no value is stored.
Upon successful completion, time(2) returns the value of time. Otherwise a value of -1 is returned and the global variable errno is set to indicate the error.
The following error codes may be set in errno
The time(2) call will also return -1 if the date is not in the range of 1970 to 2105.