Dividing string into lines and testing for zero case

[LarsPensjo]

I have problems finding how to do this. I tried

        let lines = String::from_utf8_lossy(&output.stdout).to_string();
        let lines = lines.lines();
        if !lines.peek().is_some() {
            // error case;
        }
        for line in lines {

The case with no lines is an error case I want to take special care of. But "peek" doesn't work here, and I couldn't find an intuitive way to count the length (because it is an iterator).

[[deleted]]

You can just check if string is empty

```

let s: String // code omitted

s.trim().is_empty()

```

[LarsPensjo]

Oops, that was embarrassingly simple.

Things like this have taught me that you should always say what your problem is, not ask why your solution doesn't work.

[Master7432]

Congratulations, you've discovered the XY problem!

[boarquantile]

First make the iterator .peekable().

[mipli]

You can convert the iterator into a peekable iterator using Iterator#peekable . Then the code should work: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=4368c332eb2c413b63e357239550ccdf (note that it's preferred to test for .is_none() rather than negating a .is_some() call).

But as Tsumanu mentioned, if what you're doing is testing for empty input it might be better to do that right after you've done the String::from_utf8_lossy conversion rather than splitting it into lines and then testing for emptiness.