Collections and Iterators

Rust's standard library provides powerful collection types that store data on the heap, along with an iterator system that enables functional-style data processing with zero-cost abstractions.

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Vec — Growable Arrays

A Vec<T> is a growable, heap-allocated array:

// Creating vectors
let mut v: Vec<i32> = Vec::new();
let v2 = vec![1, 2, 3]; // macro shorthand

// Adding elements
v.push(1);
v.push(2);
v.push(3);

// Accessing elements
let third = &v[2];           // panics if out of bounds
let third = v.get(2);         // returns Option<&i32>

Common Vec Methods

Method	Description
push(value)	Add an element to the end
pop()	Remove and return the last element
len()	Number of elements
is_empty()	Check if empty
contains(&value)	Check if a value exists
sort()	Sort in place
dedup()	Remove consecutive duplicates
retain(|x| pred)	Keep only elements matching a predicate
iter()	Create an iterator

Iterating Over a Vec

let v = vec![1, 2, 3];

// Immutable iteration
for val in &v {
    println!("{val}");
}