rust check if key in hashmap

To check if a key exists in a HashMap in Rust, you can use the contains_key method. Here's an example:

use std::collections::HashMap;

fn main() {
    let mut map = HashMap::new();
    map.insert("key1", "value1");
    map.insert("key2", "value2");

    let key = "key1";
    if map.contains_key(key) {
        println!("The key '{}' exists in the HashMap.", key);
    } else {
        println!("The key '{}' does not exist in the HashMap.", key);
    }
}

In this example, we create a new HashMap called map and insert two key-value pairs into it. We then define a variable key and check if it exists in the HashMap using the contains_key method. If the key exists, we print a message indicating that it exists. Otherwise, we print a message indicating that it does not exist.

You can replace "key1" with any key you want to check in the HashMap.