Rust Array Sorting & Slicing

Rust Vectors, Arrays, and Slices: Exercise-8 with Solution

Write a Rust program that creates an array of random integers of size 12. Sort the array in descending order and slice it to get a sub-array containing the top 4 elements. Print the sub-array.

Sample Solution:

Rust Code:

use rand::prelude::*; // Import the necessary traits for random number generation

fn main() {
    // Declare an array to store random integers with size 12
    let mut numbers: [i32; 12] = [0; 12]; // Declare an array initialized with zeros

    // Initialize the random number generator
    let mut rng = thread_rng(); // Create a random number generator instance

    // Generate random integers and add them to the array
    for i in 0..12 {
        numbers[i] = rng.gen_range(1..=100); // Generate a random integer between 1 and 100
    }

    // Sort the array in descending order
    numbers.sort_by(|a, b| b.cmp(a)); // Sort the array using a custom comparator to sort in descending order

    // Slice the array to get a sub-array containing the top 4 elements
    let top_four = &numbers[0..4]; // Slice the array from index 0 to index 3 (inclusive)

    // Print the sub-array containing the top 4 elements
    println!("Top four elements: {:?}", top_four); // Print the sub-array using debug formatting
}

Output:

Top four elements: [99, 88, 73, 57]

Explanation:

Here is a brief explanation of the above Rust code:

• use rand::prelude::*;: This line imports the necessary traits for random number generation from the "rand" crate.
• fn main() { ... }: This line defines the main function, which is the entry point of the Rust program.
• let mut numbers: [i32; 12] = [0; 12];: This line declares an array named 'numbers' of type [i32; 12] (array of integers with size 12) and initializes it with zeros.
• let mut rng = thread_rng();: This line creates an instance of the random number generator.
• for i in 0..12 { ... }: This line starts a loop to generate 12 random integers.
• numbers[i] = rng.gen_range(1..=100);: This line generates a random integer between 1 and 100 using the "gen_range()" method and assigns it to the i-th element of the numbers array.
• numbers.sort_by(|a, b| b.cmp(a));: This line sorts the 'numbers' array in descending order using the "sort_by()" method with a custom comparator.
• let top_four = &numbers[0..4];: This line slices the 'numbers' array to get a sub-array containing the top 4 elements.
• println!("Top four elements: {:?}", top_four);: This line prints the sub-array containing the top 4 elements to the console using debug formatting. The {:?} format specifier prints the elements of the array slice.

Rust Code Editor:

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