CODEWITHSUNDEEP
c++timec++-chronoelapsedtime
Xetron
Xetron

Reputation: 53

How to get the time between two points in time

I try to get the time elapsed between two points in time in milliseconds as integer or in seconds as double. I'm trying to put constant acceleration of 4m/s² on something. I got this already:

int main() {
    double accel = 4, velocity = 0;

    auto start = chrono::system_clock::now();
    sleep(3);
    auto ende = chrono::system_clock::now();

    chrono::duration<double> elapsed_seconds = ende - start;
    velocity += accel * elapsed_seconds;  //This is where I don't know what to put instead of "elapsed_seconds"

    cout << "Velocity after " << elapsed_seconds << "s is " << velocity << "m/s" << endl;
    return 0;
}

But as you might see it doesn't work. I already found something like

chrono::duration_cast<ms>(elapsed_time);

but I can't get it to work. Do you have any ideas?

Upvotes: 1

Views: 995

Answers (2)

Apples
Apples

Reputation: 3225

To get the seconds as a double:

auto seconds = chrono::duration<double>(ende - start);
auto val = seconds.count();

To get milliseconds:

auto ms = chrono::duration_cast<chrono::milliseconds>(ende - start);
auto val = ms.count();

Be careful when using duration_cast, you can lose precision.

Upvotes: 2

foreverska
foreverska

Reputation: 585

It's maybe a little strange to say you "count" a double but elapsed_seconds.count() will return the underlying value.

Upvotes: 3

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