Rust HashMap Merging & Printing

Rust Arrays: Exercise-7 with Solution

Write a Rust program that merges two HashMaps into one and print the resulting HashMap.

Sample Solution:

Rust Code:

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

fn main() {
    // Create two HashMaps to store key-value pairs
    let mut first_map: HashMap<&str, i32> = HashMap::new(); // First HashMap
    let mut second_map: HashMap<&str, i32> = HashMap::new(); // Second HashMap

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

    // Insert some key-value pairs into the second HashMap
    second_map.insert("c", 3);
    second_map.insert("d", 4);

    // Print the original HashMaps
    println!("First HashMap: {:?}", first_map);
    println!("Second HashMap: {:?}", second_map);

    // Merge the two HashMaps into one
    let mut merged_map = first_map.clone(); // Create a clone of the first HashMap
    merged_map.extend(second_map); // Extend the first HashMap with the key-value pairs from the second HashMap

    // Print the resulting merged HashMap
    println!("Merged HashMap: {:?}", merged_map);
}

Output:

First HashMap: {"b": 2, "a": 1}
Second HashMap: {"d": 4, "c": 3}
Merged HashMap: {"d": 4, "a": 1, "b": 2, "c": 3}

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 first_map: HashMap<&str, i32> = HashMap::new();: This line creates an empty HashMap named 'first_map' with keys of type &str (string slice) and values of type "i32".
• let mut second_map: HashMap<&str, i32> = HashMap::new();: This line creates another empty HashMap named 'second_map' with the same key-value types as "first_map".
• first_map.insert("a", 1);: This line inserts a key-value pair into the 'first_map' HashMap, where the key is the string slice "a" and the value is the integer 1. Similar lines insert additional key-value pairs into the 'first_map' HashMap.
• second_map.insert("c", 3);: This line inserts key-value pairs into the 'second_map' HashMap in a similar manner as done for the 'first_map'.
• println!("First HashMap: {:?}", first_map);: This line prints the contents of the first HashMap before the merge operation.
• println!("Second HashMap: {:?}", second_map);: This line prints the contents of the second HashMap before the merge operation.
• let mut merged_map = first_map.clone();: This line creates a clone of the first HashMap to avoid modifying the original HashMap. The clone is stored in the variable 'merged_map'.
• merged_map.extend(second_map);: This line extends the 'merged_map' HashMap with the key-value pairs from the 'second_map' HashMap using the "extend()" method.
• println!("Merged HashMap: {:?}", merged_map);: This line prints the resulting merged HashMap after the merge operation.

Rust Code Editor:

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