Running time

[Rajeev]

I want to calculate the running time of my program, which runs for a
long time(~ a day). This is what I am doing in my code:


#include <time.h>
clock_t tend, tstart;
tstart = clock();

\* Body of Code *\

tend = clock();
Running Time = ((double) (tend - tstart) / (double) CLOCKS_PER_SEC));

But for my codes which run for a long time, I am not getting the right
value for the running time variable. Please help me out!!

Thanks
Rajeev.