Hi, first of all sorry if it’s not the place to ask (I’ll delete the post if it’s the case).
I started to learn Rust a few days ago and I’m currently doing the rustlings course. I’m at the exercise error_handling/errors2.rs. I’ve succeed to make it compile using the ? operator which I find kinda easy to understand.
My problem is the following: It’s stated in the exercise that there’s another solution. After looking at the hint, I know that the other solution is the use of match. I’ve kept looking at the docs, the examples and also StackOverflow posts but I can’t make it work since I really don’t understand how it’s supposed to work.
Here's what I tried:
pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
let processing_fee = 1;
let cost_per_item = 5;
let qty = item_quantity.parse();
match qty {
Ok(qty) => qty * cost_per_item + processing_fee,
Err(e) => Err(e),
};
}
And here's what the compiler give:
expected enum 'Result<i32, ParseIntError>' found unit type '()'
You also don’t need that match there. You should be able to do :
let qty = item_quantity.parse()?; let whatever = qty * cost_per_item + processing_fee; Ok(whatever)Check out the sections on error handling in the rust book.
That’s what I did at first but I wanted to understand how to use match since they stated that we could use both case.