1
0
Fork 0
mirror of https://github.com/notohh/rustlings.git synced 2024-12-20 23:48:09 -05:00
rustlings/solutions/23_conversions/as_ref_mut.rs
2024-09-22 10:49:55 +02:00

60 lines
1.5 KiB
Rust

// 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.
// Obtain the number of bytes (not characters) in the given argument
// (`.len()` returns the number of bytes in a string).
fn byte_counter<T: AsRef<str>>(arg: T) -> usize {
arg.as_ref().len()
}
// Obtain the number of characters (not bytes) in the given argument.
fn char_counter<T: AsRef<str>>(arg: T) -> usize {
arg.as_ref().chars().count()
}
// Squares a number using `as_mut()`.
fn num_sq<T: AsMut<u32>>(arg: &mut T) {
let arg = arg.as_mut();
*arg *= *arg;
}
fn main() {
// You can optionally experiment here.
}
#[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));
}
#[test]
fn mut_box() {
let mut num: Box<u32> = Box::new(3);
num_sq(&mut num);
assert_eq!(*num, 9);
}
}