RUST Map Object

In RUST, The type HashMap stores a mapping of keys of type K to values of type V. It does this via a hashing function, which determines how it places these keys and values into memory. Many programming languages support this kind of data structure, but they often use a different name, such as hash, map, object, hash table, dictionary, or associative array, just to name a few.

To create a new Map (HashMap) object in RUST we use std::collections::HashMap library.

Example of creating Map Object

use std::collections::HashMap;

fn main() {
 let solar_distance = HashMap::from([
    ("Mercury", 0.4),
    ("Venus", 0.7),
    ("Earth", 1.0),
    ("Mars", 1.5),
 ]);
}

RUST Iterate through Elements in Map Objects

Below example shows how we can iterate through elements in a Map

use std::collections::HashMap;

fn main() {

    let solar_distance = HashMap::from([
        ("Mercury", 0.4),
        ("Venus", 0.7),
        ("Earth", 1.0),
        ("Mars", 1.5),
    ]);

    for (key, value) in &solar_distance {
        println!("{}: \"{}\"", key, value);
    }
}

Output

Venus: "0.7"
Earth: "1"
Mercury: "0.4"
Mars: "1.5"

RUST Iterate through Elements in Map Objects

Below example shows how we can iterate through elements in a Map

use std::collections::HashMap;

fn main() {

    let solar_distance = HashMap::from([
        ("Mercury", 0.4),
        ("Venus", 0.7),
        ("Earth", 1.0),
        ("Mars", 1.5),
    ]);

    for (key, value) in &solar_distance {
        println!("{}: \"{}\"", key, value);
    }
}

Output

Venus: "0.7"
Earth: "1"
Mercury: "0.4"
Mars: "1.5"

RUST get exact element value in Map Objects

Below example shows how we can get an exact element in a RUST Map

use std::collections::HashMap;
fn main() {
    let mut map = HashMap::new();
    map.insert(1, "Jhon");
    map.insert(5, "William");
    println!("Name of key needed is {}", map.get(&5).unwrap());
}

Output

Name of key needed is William

Conclusion

In this page (written and validated by A. Gawali) you learned about Rust Map Object - HashMap . What's Next? If you are interested in completing Rust tutorial, your next topic will be learning about: Rust Enum.

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