LANGUAGE » RUST

Iterators

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Basic

With iterators it is possible to chain several operations, and at the end use collect to save the result as a collection.

Double the value of every element:

rust

let numbers = 1..=3;
let doubled: Vec<i32> = numbers.map(|num| num * 2).collect();

Convert a char slice to a String:

rust

let chars = &['H', 'e', 'l', 'l', 'o'];
let text: String = chars.iter().collect();

Method	Description
`collect`	Transforms an iterator into a collection. May use turbofish `::<>` annotation.
`enumerate`	Creates an iterator which gives the current iteration count as well as the next value.
`map`	Takes a closure and creates an iterator which calls that closure on each element.
`rev`	Reverses an iterator’s direction.

To get the current index while looping an iterator, use enumerate:

rust

for (i, line) in text.lines().enumerate() {
    println!("Line {}: {}", i, line);
}

Same but backwards:

rust

for (i, line) in text.lines().enumerate().rev() {
    println!("Line {}: {}", i, line);
}