Graceful error handling

One of the most loved features of Rust is the way it lets you handle errors. The Result type is a powerful tool that allows you to handle errors in a way that is both safe and expressive. In this challenge, you will be working with the Result<T, E> type to handle errors in a graceful way.

The Result<T, E> itself is an enum that has two variants: Ok(T) and Err(E). The Ok variant is used to represent a successful computation that returns a value of type T. The Err variant is used to represent an error that returns a value of type E.

When you have a function that can fail, you can use the Result type to return the result of the computation. If the computation is successful, you can return the success variant of Result with the value of the computation. If the computation fails, you can return the error variant of Result with an error message that explains what went wrong.

Your task

In this challenges, you're given a function, parse_percentage(input: &str) -> Result<u8, String> that takes a string as input and returns a Result type. The function should parse the input string as a percentage and return the percentage as a u8 if the input is valid. If the input is invalid, the function should return an error message as a String.

Parsing from a string to a number can fail for many reasons. For example, the input string may not be a valid number, or it may be a valid number but not a valid percentage. Your task is to handle these errors gracefully and return an error message that explains what went wrong.

Complete the function, if the parsing was successful return a success variant of the Result, if there was an error in parsing, return an error variant of the Result with an error message.

Requirements
  • If the parse was successful, the function should return the success variant of Result with the percentage as a u8.
  • If the number was out of range (not between 0 and 100), the function should return the error with String "Percentage out of range".
  • If the string was not a valid number, the function should return the error with String "Invalid input".

Example

 
let result = parse_percentage("50");
assert_eq!(result, Ok(50));
 
let result = parse_percentage("101");
assert_eq!(result, Err("Percentage out of range".to_string()));
 
let result = parse_percentage("abc");
assert_eq!(result, Err("Invalid input".to_string()));