public/subjects/borrow_me_the_reference

borrow_me_the_reference

Instructions

Ownership is Rust's most unique feature. It enables Rust to make memory safety guarantees without needing a garbage collector. You must have a good understanding of ownership in rust.

Create the following functions:

• delete_and_backspace: which receives a borrowed string, and processes it. - represents the backspace key and + represents the delete key, so that "helll-o" and "he+lllo" are both converted to "hello". The - and + characters should be removed from the string.

• is_correct: which borrows a Vector of string literals representing simple addition and subtraction equations. The function should replace the correct equations with ✔, and the wrong ones with ✘. It should return a usize with the percentage of correct equations.

Expected Functions

pub fn delete_and_backspace(s: &mut String) {
}

pub fn is_correct(v: &mut Vec<&str>) -> usize {
}

Dependencies

meval = "0.2"

Usage

Here is a program to test your function

use borrow_me_the_reference::{delete_and_backspace, is_correct};

fn main() {
	let mut a = String::from("bpp--o+er+++sskroi-++lcw");
	let mut b: Vec<&str> = vec!["2+2=4", "3+2=5", "10-3=3", "5+5=10"];

	// - If a value does **not implement Copy**, it must be **borrowed** and so will be passed by **reference**.
	delete_and_backspace(&mut a); // the reference of  the value
	let per = is_correct(&mut b); // the reference of  the value

	println!("{:?}", (a, b, per));
	// output: ("borrow", ["✔", "✔", "✘", "✔"], 75)
}

And its output

$ cargo run
("borrow", ["✔", "✔", "✘", "✔"], 75)
$

Notions

• ownership
• meval