Rust Memory Leak Demo

memory_leak,rs

#[allow(dead_code)]
struct Entity {
    level: u8,
    health: u8
}

fn show_vector (next: &Option<Entity>) -> char {
    match next {
        &Some(_) => '0',
        &None   => '.'
    }
}

fn main(){

    // First define an "empty" element
    let empty_entity: &Option<Entity> = &None;

    // And now an "empty" vector
    let mut entity_vec: Vec<&Option<Entity>> =vec![empty_entity; 10];

    // Let's add some actual entities to the vector
    entity_vec[1] = &Some (Entity {health: 83, level: 5});
    entity_vec[3] = &Some (Entity {health: 81, level: 12});
    entity_vec[7] = &Some (Entity {health: 97, level: 3});

    // And now we can visualise the vector
    for next in entity_vec.iter() {
        print!("{}", show_vector (next));
    }

    println!("");

    /*
     * The main program logic goes here.
     * Depending on the actions of the entites, they will either gain or lose health.
     * If they reach maximum health, they spawn new entity but lose some health.
     * If their health reaches zero they die.
     */

    // Two of the entities have reached zero health so we kill them off.
    entity_vec[1] = empty_entity;
    entity_vec[7] = empty_entity;

    // Now let's look at the vector
    for next in entity_vec.iter() {
        print!("{}", show_vector (next));
    }

    println!("");

    // But where did the two entites go?  Memory leak?

}