Question

there’s a function that I want to test the time of: function()

I am not sure how to do this in C, here’s the pseudocode of what I want to do:

int main()
{
int startTime = getTime();
function();
int endTime = getTime();
print endTime - startTime;
}

How is this done in C?

Answer 1

Unfortunately there is no way to do this using ANSI C. However, you can do it using gettimeofday, a POSIX function:

#include <sys/time.h>

struct timeval tv;
struct timeval start_tv;

gettimeofday(&start_tv, NULL);

// call your function here

double elapsed = 0.0;

gettimeofday(&tv, NULL);
elapsed = (tv.tv_sec - start_tv.tv_sec) +
  (tv.tv_usec - start_tv.tv_usec) / 1000000.0;

Alternatively, if you want the execution time of your entire program, you could also just run time ./your_program on the command line.

Finally, if you are on Windows, you can use the timeGetTime function.