#Rustlings - exercises - vecs2.rs
1 messages · Page 1 of 1 (latest)
I just deleted my whole question...
Ok, so i've been doing the Rustlings to learn Rust and basically I'm stuck at the vecs2.rs exercise, here's the code I have so far (I managed to do the first half, but I can't wrap my head around the second half
// vecs2.rs
// A Vec of even numbers is given. Your task is to complete the loop
// so that each number in the Vec is multiplied by 2.
//
// Make me pass the test!
//
// Execute `rustlings hint vecs2` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE
fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
for i in v.iter_mut() {
// TODO: Fill this up so that each element in the Vec `v` is
// multiplied by 2.
*i *= 2;
}
// At this point, `v` should be equal to [4, 8, 12, 16, 20].
v
}
fn vec_map(v: &Vec<i32>) -> Vec<i32> {
v.iter().map(|num| {
// TODO: Do the same thing as above - but instead of mutating the
// Vec, you can just return the new number!
???
}).collect()
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_vec_loop() {
let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
let ans = vec_loop(v.clone());
assert_eq!(ans, v.iter().map(|x| x * 2).collect::<Vec<i32>>());
}
#[test]
fn test_vec_map() {
let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
let ans = vec_map(&v);
assert_eq!(ans, v.iter().map(|x| x * 2).collect::<Vec<i32>>());
}
}
here's the error in the console
⚠️ Compiling of exercises/vecs/vecs2.rs failed! Please try again. Here's the output:
error: expected expression, found `?`
--> exercises/vecs/vecs2.rs:26:9
|
26 | ???
| ^ expected expression
error: aborting due to previous error
I'm using gitpod if that has an impact on anything
if you just want the straight answer: ||.map(|num| num * 2). the test_vec_map test actually does the exact same which is a bit weird to show like that||
I dont know what to explain better than rustlings already does there. I guess you can look at the documentation of the functions there, specifically map, to understand what supposed to happen better