What is the IntoIterator trait

The IntoIterator trait converts a type into an iterator, enabling it to be used in for loops and iterator methods. Implementing this trait allows your custom types to be consumed item-by-item just like standard collections.

use std::iter::IntoIterator;

struct MyCollection {
    items: Vec<i32>,
}

impl IntoIterator for MyCollection {
    type Item = i32;
    type IntoIter = std::vec::IntoIter<i32>;

    fn into_iter(self) -> Self::IntoIter {
        self.items.into_iter()
    }
}

The IntoIterator trait is a rule that tells Rust how to turn a container into a list of items you can go through one by one. It matters because it lets you use custom data structures in for loops just like you do with vectors or arrays. Think of it as a universal adapter that plugs any collection into the standard looping mechanism.