What Is the Entry API for HashMap in Rust?

The entry API for HashMap in Rust is the entry method, which allows you to insert or update a value in a single operation without needing to check if the key exists first. You call entry on the map with a key, then chain a method like or_insert to provide a default value if the key is missing, or modify the existing value if it is present.

use std::collections::HashMap;

let mut scores = HashMap::new();
scores.entry(String::from("Blue")).or_insert(10);

The entry API is a shortcut for checking if a key exists in a map and then either adding a new value or updating the old one. It saves you from writing repetitive code to handle both scenarios separately. Think of it like a vending machine that automatically adds a snack if you don't have one, or gives you a discount if you already do.