// Rust version that takes several seconds to execute based on the size of Ent:

// Strangely runs fine on Playground but not from the executable generated by rustc on desktop

struct Ent
{
    x : i32,
    foo : [i32; 100000]
}

impl Ent
{
    fn do_thing(&mut self)
    {
        self.x += 2;
    }
}

fn main()
{
    let mut list : Vec<Ent> = Vec::new();

    for _ in 0..100
    {
        let entity = Ent { x : 0, foo : [0; 100000] };

        list.push(entity);
    }

    for _ in 0..4000000
    {
        for entity in &mut list
        {
            entity.do_thing();
        }
    }
}

// CPP version that executes instantaneously:

/*

#include <vector>

struct Ent
{
    int x;
    int foo[100000];

    Ent() : x(0), foo() {}

    void doThing()
    {
        x += 2;
    }
};

int main()
{
    std::vector<Ent> list;

    for (int i = 0; i < 100; ++i)
    {
        Ent entity;

        list.push_back(entity);
    }

    for (int i = 0; i < 4000000; ++i)
    {
        for (auto iter = list.begin(); iter != list.end(); ++iter)
        {
            iter->doThing();
        }
    }

    return 0;
}

*/