Collecting iterator into existing vec

1

  1. I think there's a one line solution. I have checked the Iterator / Vec documentation, but can not find which function to use.

  2. I have the following:




pub fn foo() {
    let input = vec![1_i32, 2, 3];
    let output = vec![1_i32, 2, 4];

    let t: Vec<i32> = input.iter().map(|x| x + 1).collect();
}
  1. What happens here is that the mapped results are dumped into a new vector t ... what I want is for the iterator results to be appended to the end of "output". Is there a way to "collect into an existing vector"?
2

You can use the extend method on the Vec.

It comes from this trait

2 Likes
3 
let mut output = vec![1_i32, 2, 4];
output.extend(input.iter().map(|x| x + 1));
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4

@vitalyd , @RustyYato :

extend solved it. thanks!