Rust Brain Teasers

Puzzle 8

Walks Like a Duck, Quacks Like a Duck

quack/src/main.rs

fn double_it(n: u64, _: i32) -> u64 {
    n * 2
}

fn main() {
    let one: i32 = 1;
    let n = double_it(one as _, 3);
    println!("{}", n);
}

Guess the Output
	Try to guess what the output is before moving to the next page.

The program will display the following output, showing no warnings or errors:

2

Discussion

We find two surprises:

• You can name a function parameter ...