Guessing Game: Number input fails to produce Option int, instead produces Option none

[listless]

Running the Guessing Game program at the end of Chapter 11, it does not seem to recognise when I enter a number, instead always producing options of type none, I fixed this by changing
let num = from_str::<int>(input.slice_to(input.len() - 1));
to
let num = from_str::<int>(input.slice_to(input.len() - 2));
because I suspected that this method was trying to remove the \n from the end of the input string, and \n would be two characters.

Sorry, new to github so I believed this would be the best place to post about this, can this problem be confirmed?

[steveklabnik]

This is the perfect place, thank you.

Hmmm, strange. I tried the code and it worked for me. What platform are you on?

[listless]

I'm on 64-bit Windows 7, strange.

[steveklabnik]

Hm, I wonder if that's it.

[listless]

When I run this:

 use std::io::buffered::BufferedReader;
 use std::io;
 
 fn main() {
     println("Input: ");
     let mut reader = BufferedReader::new(io::stdin());
     let input = reader.read_line().unwrap_or(~"nothing");
     println!("{:?}", input.len());
 }

And only press enter, I get an output of 2u, could the output be different on different systems?

[Kimundi]

Could it be that on windows it reads \r\n, while on different systems its only \n?

[listless]

hmm, maybe.
Testing on a linux machine and I get an output of 1u from the program I posted

Edit: After looking around, I agree with Kimundi that window's use of \r\n as oppose to \n may most likely be the cause of the problem, maybe this could be resolved by BufferReader's read_line() discarding the ending \r and \n when returning the string?

http://static.rust-lang.org/doc/master/std/io/struct.BufferedReader.html

[listless]

After looking at http://adridu59.github.io/rust-tuts/tutorial/tutorial.html ,
I think another way of converting from str to int could be to use:

let num = from_str::<int>(input.trim_right_chars(& &['\n', '\r']));

This should work for both Windows, OS X and Linux systems, as it'll get rid of the \n, and optionally the \r if it exists.

http://static.rust-lang.org/doc/master/std/str/trait.StrSlice.html#tymethod.trim_right_chars

[steveklabnik]

This is going to be changed for 0.11. Please let me know if it still acts up with the new code.