How to get value from Vec::pop()?

I see pop() method of vector returns an Option type. What the right way to get pop() value to a variable?

let mut queue: Vec<[usize; 2]> = Vec::new();
queue.push([1, 2]);
queue.push([3, 4]);

let coords = queue.pop();
println!("{}, {}", coords[0], coords[1]);

error[E0608]: cannot index into a value of type `std::option::Option<[usize; 2]>`
  --> src/main.rs:99:24
   |
99 |     println!("{}, {}", coords[0], coords[1]);
   |

Solution

If you know for a fact that queue will never be empty when you call pop on it, you can unwrap the option:

let coords = queue.pop().unwrap();

Otherwise, you can match on it and do whatever handling you need to in the None case:

let coords = match queue.pop() {
    Some(top) => top,
    None => {
        // … handling …
    }
};

Another possibility, useful if you only want to do something when the option is Some, is use if let:

if let Some(coords) = queue.pop() {
    println!("{}, {}", coords[0], coords[1]);
}