How to Reverse a List in Rust

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Rust is a modern, high-performance systems programming language that offers many features for efficient memory management and safe concurrency.

In this post, we will look at how to reverse a list in Rust, a common programming task that can be accomplished with just a few lines of code.

In Rust, a list is called a vector, which is a dynamic array that can grow or shrink as needed.

The Vec type is provided by Rust's standard library, and it is a generic type that can hold any type of data.

We will use a Vec of integers to demonstrate how to reverse a list in Rust.

How to reverse a list in Rust

Create a list to be reversed:

let mut list = vec![1, 2, 3, 4, 5];

This creates a mutable Vec of integers with the values 1, 2, 3, 4, and 5.

Determine the length of the list:

let length = list.len();

This uses the len method of the Vec type to get the length of the list.

Use a for loop to iterate over half of the list and swap the values at each end of the list until the entire list is reversed:

for i in 0..(length / 2) {
    let temp = list[i];
    list[i] = list[length - i - 1];
    list[length - i - 1] = temp;
}

This loop iterates over the first half of the list, and for each iteration, it swaps the value at the current index with the value at the corresponding index from the end of the list.

For example, on the first iteration, it swaps the value at index 0 with the value at index 4 (i.e., length - 0 - 1).

The list should now be reversed. You can print it out to check:

println!("{:?}", list); // Output: [5, 4, 3, 2, 1]

This prints out the reversed list.

Alternatively, you can define a separate function to handle the reversal of the list:

fn reverse_list(list: &mut Vec<i32>) {
    let length = list.len();
    for i in 0..(length / 2) {
        let temp = list[i];
        list[i] = list[length - i - 1];
        list[length - i - 1] = temp;
    }
}

fn main() {
    let mut list = vec![1, 2, 3, 4, 5];
    reverse_list(&mut list);
    println!("{:?}", list); // Output: [5, 4, 3, 2, 1]
}

This function takes a mutable reference to the list as an argument and performs the same swapping operation in place, resulting in a reversed list.

Summary

In conclusion, reversing a list in Rust is a straightforward task that can be accomplished with just a few lines of code.

Rust's efficient memory management and safe concurrency features make it an excellent choice for systems programming, and its expressive syntax makes it easy to write clear and concise code.

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