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.