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:

  1. pub trait Iterator {
  2.     // The type being iterated over.
  3.     type Item;
  5.     // `any` takes `&mut self` meaning the caller may be borrowed
  6.     // and modified, but not consumed.
  7.     fn any<F>(&mut self, f: F) -> bool where
  8.         // `FnMut` meaning any captured variable may at most be
  9.         // modified, not consumed. `Self::Item` states it takes
  10.         // arguments to the closure by value.
  11.         F: FnMut(Self::Item) -> bool {}
  12. }
  1. fn main() {
  2.     let vec1 = vec![1, 2, 3];
  3.     let vec2 = vec![4, 5, 6];
  5.     // `iter()` for vecs yields `&i32`. Destructure to `i32`.
  6.     println!("2 in vec1: {}", vec1.iter()     .any(|&x| x == 2));
  7.     // `into_iter()` for vecs yields `i32`. No destructuring required.
  8.     println!("2 in vec2: {}", vec2.into_iter().any(| x| x == 2));
  10.     let array1 = [1, 2, 3];
  11.     let array2 = [4, 5, 6];
  13.     // `iter()` for arrays yields `&i32`.
  14.     println!("2 in array1: {}", array1.iter()     .any(|&x| x == 2));
  15.     // `into_iter()` for arrays unusually yields `&i32`.
  16.     println!("2 in array2: {}", array2.into_iter().any(|&x| x == 2));
  17. }

See also:

std::iter::Iterator::any