CODEWITHSUNDEEP
rustoption-type
Ibolit
Ibolit

Reputation: 9720

Using while let with two variables simultaneously

I'm learning Rust and have been going through leetcode problems. One of them includes merging two linked lists, whose nodes are optional. I want to write a while loop that would go on until at least 1 node becomes None, and I was trying to use the while let loop for that.

However, it looks like the while let syntax supports only one optional, e.g.:

while let Some(n) = node {
   // do stuff
}

but I can't write

while let Some(n1) = node1 && Some(n2) = node2 {
}

Am I misunderstanding the syntax? I know I can rewrite it with a while true loop, but is there a more elegant way of doing it?

Also, can one do multiple checks with if let? Like if let None=node1 && None=node2 {return}

Upvotes: 4

Views: 1359

Answers (2)

Chayim Friedman
Chayim Friedman

Reputation: 70830

In addition to what @Netwave said, on nightly you can use the unstable let_chains feature:

#![feature(let_chains)]

while let Some(n1) = node1 && let Some(n2) = node2 {
    // ...
}

Upvotes: 8

Netwave
Netwave

Reputation: 42678

You can pattern match with Option::zip:

while let Some((n1, n2)) = node1.zip(node2) {
    ...
}

Upvotes: 11

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