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fix(errors3): Update hint

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Closes #185.
This commit is contained in:
marisa 2019-11-11 13:37:43 +01:00
parent ad03d180c9
commit dcfb427b09
1 changed files with 3 additions and 18 deletions
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21
exercises/error_handling/errors3.rs
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@ -1,8 +1,7 @@
// 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--
// we can't use the `?` operator in the `main()` function! Why not?
// What should we do instead? Scroll for hints!
// `total_cost` function from the previous exercise. It's not working though!
// Why not? What should we do to fix it? Scroll for hints!
use std::num::ParseIntError;
@ -45,18 +44,4 @@ pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
// Since the `?` operator returns an `Err` early if the thing it's trying to
// do fails, you can only use the `?` operator in functions that have a
// `Result` as their return type.
// Hence the error that you get if you run this code is:
// ```
// error[E0277]: the `?` operator can only be used in a function that returns `Result` (or another type that implements `std::ops::Try`)
// ```
// So we have to use another way of handling a `Result` within `main`.
// Decide what we should do if `pretend_user_input` has a string value that does
// not parse to an integer, and implement that instead of using the `?`
// operator.
// If other functions can return a `Result`, why shouldn't `main`?