armanriazi rust collection hashmap key modify

To modify a key in a HashMap in Rust, you can use the entry method to access the key-value pair. The entry method returns an Entry enum, which allows you to modify the value associated with the key.

Here's an example:

use std::collections::HashMap;

fn main() {
    let mut map = HashMap::new();
    map.insert("key", "value");

    let entry = map.entry("key").or_insert("new_value");
    *entry = "modified_value";

    println!("{:?}", map);
}

In this example, we create a HashMap and insert a key-value pair into it. Then, we use the entry method to access the key-value pair for the key "key". If the key exists, the entry method returns a mutable reference to the value. If the key doesn't exist, it inserts the specified value and returns a mutable reference to the newly inserted value.

We use the dereference operator * to modify the value associated with the key. Finally, we print the modified HashMap.

Output:

{"key": "modified_value"}

This code snippet demonstrates how to modify a key in a HashMap in Rust.