Vectors

A Vec<T> is a growable list of values of the same type, allocated on the heap. The vec! macro is the usual way to create one with initial values.

fn main() {
    let numbers = vec![1, 2, 3, 4, 5];
    println!("{:?}", numbers);

    let sum: i32 = numbers.iter().sum();
    println!("sum = {}", sum);
}

[1, 2, 3, 4, 5]
sum = 15

Growing and shrinking a vector

push adds an item to the end; remove takes an item out by index and returns it, shifting everything after it down. Both require the vector itself to be mutable.

fn main() {
    let mut fruits = vec!["apple", "banana", "cherry"];
    fruits.push("date");
    println!("{:?}", fruits);

    let first = fruits.remove(0);
    println!("removed: {}", first);
    println!("{:?}", fruits);
}

["apple", "banana", "cherry", "date"]
removed: apple
["banana", "cherry", "date"]

Next: iterators and closures — transforming a collection without writing a manual loop.