rustlings/exercises/conversions/as_ref_mut.rs

61 lines
1.6 KiB
Rust
Raw Permalink Normal View History

// AsRef and AsMut allow for cheap reference-to-reference conversions.
// Read more about them at https://doc.rust-lang.org/std/convert/trait.AsRef.html
// and https://doc.rust-lang.org/std/convert/trait.AsMut.html, respectively.
2022-07-15 10:50:01 +00:00
// Execute `rustlings hint as_ref_mut` or use the `hint` watch subcommand for a hint.
2020-04-08 09:00:11 +00:00
// I AM NOT DONE
// Obtain the number of bytes (not characters) in the given argument
// Add the AsRef trait appropriately as a trait bound
fn byte_counter<T>(arg: T) -> usize {
arg.as_ref().as_bytes().len()
}
// Obtain the number of characters (not bytes) in the given argument
// Add the AsRef trait appropriately as a trait bound
fn char_counter<T>(arg: T) -> usize {
arg.as_ref().chars().count()
}
2022-07-15 10:50:01 +00:00
// Squares a number using AsMut. Add the trait bound as is appropriate and
// implement the function body.
fn num_sq<T>(arg: &mut T) {
???
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn different_counts() {
let s = "Café au lait";
assert_ne!(char_counter(s), byte_counter(s));
}
#[test]
fn same_counts() {
let s = "Cafe au lait";
assert_eq!(char_counter(s), byte_counter(s));
}
#[test]
fn different_counts_using_string() {
let s = String::from("Café au lait");
assert_ne!(char_counter(s.clone()), byte_counter(s));
}
#[test]
fn same_counts_using_string() {
let s = String::from("Cafe au lait");
assert_eq!(char_counter(s.clone()), byte_counter(s));
}
2022-07-15 10:50:01 +00:00
#[test]
fn mult_box() {
let mut num: Box<u32> = Box::new(3);
num_sq(&mut num);
assert_eq!(*num, 9);
}
}