Timing algorithm: clock() vs time() in C++

Question

For timing an algorithm (approximately in ms), which of these two approaches is better:

clock_t start = clock();
algorithm();
clock_t end = clock();
double t         


        

Answer 1

How about gettimeofday()? When it is called it updates two structs (timeval and timezone), with timing information. Usually, passing a timeval struct is enough and the timezone struct can be set to NULL. The updated timeval struct will have two members tv_sec and tv_usec. tv_sec is the number of seconds since 00:00:00, January 1, 1970 (Unix Epoch) and tv_usec is additional number of microseconds w.r.t. tv_sec. Thus, one can get time expressed in very good resolution.

It can be used as follows:

#include 

struct timeval start_time;
double mtime, seconds, useconds;
gettimeofday(&start_time, NULL); //timeval is usually enough
int seconds  = start_time.tv_sec; //time in seconds
int useconds = start_time.tv_usec; //further time in microseconds
int desired_time = seconds * 1000000 + useconds; //time in microseconds