Question

I want to test which data structure is the best by looking at the run-time performance of my algorithm, how do I do it?

For example I already have a hashmap<string, int> hmp; assuming I have "apple" in my hashmap I want to know how long the following statement takes to execute: hmp["apple"].

How can I time it?

Thanks!

Answer 1

First of all take a look at my reply to this question; it contains a portable (windows/linux) function to get the time in milliseconds.

Next, do something like this:

int64 start_time = GetTimeMs64();
const int NUM_TIMES = 100000; /* Choose this so it takes at the very least half a minute to run */

for (int i = 0; i < NUM_TIMES; ++i) {
   /* Code you want to time.. */
}

double milliseconds = (GetTimeMs64() - start_time) / (double)NUM_TIMES;

All done! (Note that I haven’t tried to compile it)