Dictionary Length in Rust

In Rust, you can get the number of key-value pairs in a HashMap using the len() method:

use std::collections::HashMap;

let mut scores: HashMap<&str, i32> = HashMap::new();
scores.insert("Alice", 95);
scores.insert("Bob", 87);
scores.insert("Charlie", 72);

let n = scores.len();
println!("{}", n);  // 3

len() returns the number of entries. You can also check if it's empty with is_empty():

println!("{}", scores.is_empty());  // false
let empty: HashMap<&str, i32> = HashMap::new();
println!("{}", empty.len());    // 0