Iterator::any
Iterator::any
is a function which when passed an iterator, will return
true
if any element satisfies the predicate. Otherwise false
. Its
signature:
pub trait Iterator {
// The type being iterated over.
type Item;
// `any` takes `&mut self` meaning the caller may be borrowed
// and modified, but not consumed.
fn any<F>(&mut self, f: F) -> bool where
// `FnMut` meaning any captured variable may at most be
// modified, not consumed. `Self::Item` states it takes
// arguments to the closure by value.
F: FnMut(Self::Item) -> bool;
}
fn main() { let vec1 = vec![1, 2, 3]; let vec2 = vec![4, 5, 6]; // `iter()` for vecs yields `&i32`. Destructure to `i32`. println!("2 in vec1: {}", vec1.iter() .any(|&x| x == 2)); // `into_iter()` for vecs yields `i32`. No destructuring required. println!("2 in vec2: {}", vec2.into_iter().any(|x| x == 2)); // `iter()` only borrows `vec1` and its elements, so they can be used again println!("vec1 len: {}", vec1.len()); println!("First element of vec1 is: {}", vec1[0]); // `into_iter()` does move `vec2` and its elements, so they cannot be used again // println!("First element of vec2 is: {}", vec2[0]); // println!("vec2 len: {}", vec2.len()); // TODO: uncomment two lines above and see compiler errors. let array1 = [1, 2, 3]; let array2 = [4, 5, 6]; // `iter()` for arrays yields `&i32`. println!("2 in array1: {}", array1.iter() .any(|&x| x == 2)); // `into_iter()` for arrays yields `i32`. println!("2 in array2: {}", array2.into_iter().any(|x| x == 2)); }