rustHow to create a HashMap of structs in Rust?

A HashMap of structs in Rust can be created using the HashMap type from the std::collections module. The HashMap type requires a key and a value type to be specified. The key type must implement the Eq and Hash traits, while the value type can be any type.

Example code

use std::collections::HashMap;

#[derive(Debug)]
struct Person {
    name: String,
    age: u32,
}

fn main() {
    let mut map = HashMap::new();
    map.insert("John", Person {
        name: "John".to_string(),
        age: 30,
    });
    map.insert("Alice", Person {
        name: "Alice".to_string(),
        age: 25,
    });
    println!("{:?}", map);
}

Output example

{"John": Person { name: "John", age: 30 }, "Alice": Person { name: "Alice", age: 25 }}

Code explanation

1. use std::collections::HashMap;: This imports the HashMap type from the std::collections module.
2. #[derive(Debug)]: This is a Rust attribute that allows the Person struct to be printed to the console.
3. let mut map = HashMap::new();: This creates a new HashMap with no entries.
4. map.insert("John", Person { ... });: This inserts a new entry into the HashMap with a key of type &str and a value of type Person.
5. println!("{:?}", map);: This prints the contents of the HashMap to the console.

Helpful links

• HashMap documentation
• Derive attribute documentation

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