Collections: Vector, String, and HashMap

Store groups of values with Rust’s common collection types.

Learning objectives

• Use Vec for dynamic lists
• Work with String values
• Store key-value pairs with HashMap

Vector

A Vec stores a growable list of values of the same type. It is one of the most common collection types in Rust.

String

String is a growable, owned text type. It is different from string slices and is useful when you need to modify text.

HashMap

A HashMap stores key-value pairs. It is useful for lookups such as scores, settings, and product quantities.

Example code

use std::collections::HashMap;

fn main() {
    let mut scores = vec![80, 90, 75];
    scores.push(88);

    let mut message = String::from("Hello");
    message.push_str(", Rust");

    let mut marks = HashMap::new();
    marks.insert("Alice", 90);
    marks.insert("Ben", 85);

    println!("{:?}", scores);
    println!("{}", message);
    println!("Alice: {:?}", marks.get("Alice"));
}