import std.datetime, std.random, std.range, std.stdio;
import std.math: isNaN;

struct S
{
    bool b;
    double d;
}

void main()
{
    auto arr = new S[1_000_000];

    foreach (ref a; arr)
    {
        a.b = false;
        a.d = double.nan;
    }

    auto sample = randomSample(iota(arr.length), 9 * arr.length / 10);
    foreach (s; sample)
    {
        arr[s].b = true;
        arr[s].d = 1.0;
    }

    StopWatch watch;
    size_t i = 0;

    foreach (a; arr)
    {
        watch.start();
        if (!a.b)
        {
            ++i;
        }
        watch.stop();
    }

    writeln("Time for ", arr.length, " if(boolean)'s with ", i, " counts of true: ", watch.peek.usecs, " microseconds.");

    watch.reset;
    i = 0;

    foreach (a; arr)
    {
        watch.start();
        if (isNaN(a.d))
        {
            ++i;
        }
        watch.stop();
    }

    writeln("Time for ", arr.length, " if(isNaN)'s with ", i, " counts of true: ", watch.peek.usecs, " microseconds.");
}