Rust HashMap Key Value Retrieval & Printing

Last update on December 21 2024 10:21:35 (UTC/GMT +8 hours)

Write a Rust program that retrieves the value associated with a specific key from a HashMap and print it.

Sample Solution:

Rust Code:

use std::collections::HashMap; // Import the HashMap type from the standard library

fn main() {
    // Create a HashMap to store key-value pairs
    let mut my_map: HashMap<&str, i32> = HashMap::new(); // Key: &str (string slice), Value: i32

    // Insert some key-value pairs into the HashMap
    my_map.insert("a", 1);
    my_map.insert("b", 2);
    my_map.insert("c", 3);

    // Define the key for which to retrieve the value
    let key_to_retrieve = "b";

    // Retrieve the value associated with the key from the HashMap
    let value = my_map.get(key_to_retrieve); // Get the value associated with the key

    // Print the value associated with the key, if it exists
    match value {
        Some(&v) => println!("Value associated with key '{}': {}", key_to_retrieve, v), // If the value exists, print it
        None => println!("Key '{}' does not exist in the HashMap.", key_to_retrieve), // If the value does not exist, print a message
    }
}

Output:

Value associated with key 'b': 2

Explanation:

Here is a brief explanation of the above Rust code:

• use std::collections::HashMap;: Imports the "HashMap" type from the standard library, allowing us to use HashMaps in our code.
• fn main() { ... }: Defines the main function, which is the entry point of the Rust program.
• let mut my_map: HashMap<&str, i32> = HashMap::new();: Creates an empty HashMap named 'my_map' with keys of type '&str' (string slice) and values of type "i32".
• my_map.insert("a", 1);: This line inserts a key-value pair into the "my_map" HashMap, where the key is the string slice "a" and the value is the integer 1. Similar lines insert additional key-value pairs.
• let key_to_retrieve = "b";: This line defines the key for which we want to retrieve the associated value from the HashMap.
• let value = my_map.get(key_to_retrieve);: This line retrieves the value associated with the specified key from the HashMap using the "get()" method and stores it in the variable 'value'.
• match value { ... }: This line starts a 'match' statement to handle the result of retrieving the value:
• If the value exists (Some(&v)), it prints the value associated with the key along with the key itself.
• If the value does not exist ('None'), it prints a message indicating that the key does not exist in the HashMap

Rust Code Editor:

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