35 lines
1 KiB
Rust
35 lines
1 KiB
Rust
// errors3.rs
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// This is a program that is trying to use a completed version of the
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// `total_cost` function from the previous exercise. It's not working though!
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// Why not? What should we do to fix it?
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// Execute `rustlings hint errors3` for hints!
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use std::num::ParseIntError;
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// In previous excercises we were taught that Result can output
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// i32 and ParseIntError, but nobody told us that Result can also
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// output () instead of i32... oops
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fn main() -> Result<(), ParseIntError> {
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let mut tokens = 100;
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let pretend_user_input = "8";
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let cost = total_cost(pretend_user_input)?;
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if cost > tokens {
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println!("You can't afford that many!");
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} else {
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tokens -= cost;
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println!("You now have {} tokens.", tokens);
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}
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// No need for Err() because `?` operator already handles it well
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Ok(())
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}
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pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
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let processing_fee = 1;
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let cost_per_item = 5;
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let qty = item_quantity.parse::<i32>()?;
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Ok(qty * cost_per_item + processing_fee)
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}
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