rustlings/exercises/error_handling/errors3.rs

36 lines
903 B
Rust

// errors3.rs
//
// This is a program that is trying to use a completed version of the
// `total_cost` function from the previous exercise. It's not working though!
// Why not? What should we do to fix it?
//
// Execute `rustlings hint errors3` or use the `hint` watch subcommand for a
// hint.
use std::error::Error;
use std::num::ParseIntError;
fn main() -> Result<(), Box<dyn Error>> {
let mut tokens = 100;
let pretend_user_input = "8";
let cost = total_cost(pretend_user_input)?;
if cost > tokens {
println!("You can't afford that many!");
} else {
tokens -= cost;
println!("You now have {} tokens.", tokens);
}
Ok(())
}
pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
let processing_fee = 1;
let cost_per_item = 5;
let qty = item_quantity.parse::<i32>()?;
Ok(qty * cost_per_item + processing_fee)
}