Rust Collections: Vec, HashMap and HashSet Explained with Examples

fn main() { let mut ports = vec![80, 443]; ports.push(8080); ports.push(8443); println!("{:?}", ports); println!("first = {}", ports[0]); }

match ports.get(10) { Some(port) => println!("{port}"), None => println!("No port at that index"), }

let mut scores = vec![10, 20, 30]; for score in &scores { println!("{score}"); } for score in &mut scores { *score += 5; }

use std::collections::HashMap; fn main() { let mut servers = HashMap::new(); servers.insert("api", "10.0.0.10"); servers.insert("db", "10.0.0.20"); if let Some(ip) = servers.get("api") { println!("API server: {ip}"); } }

let mut counts = HashMap::new(); counts.entry("rust").or_insert(0); *counts.entry("rust").or_insert(0) += 1;

use std::collections::HashSet; fn main() { let mut roles = HashSet::new(); roles.insert("admin"); roles.insert("editor"); roles.insert("admin"); println!("{}", roles.len()); // 2 println!("{}", roles.contains("admin")); }

use std::collections::HashMap; let key = String::from("service"); let value = String::from("payments"); let mut map = HashMap::new(); map.insert(key, value); // key and value have moved into map

use std::collections::{HashMap, HashSet}; fn main() { let items = vec!["api", "db", "api", "cache", "db", "api"]; let mut counts = HashMap::new(); let mut unique = HashSet::new(); for item in items { unique.insert(item); *counts.entry(item).or_insert(0) += 1; } println!("Counts: {counts:?}"); println!("Unique: {unique:?}"); }

cargo fmt --check cargo clippy cargo test cargo run