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Macro std::vec

macro_rules! vec {
    ( $ elem : expr ; $ n : expr ) => { ... };
    ( $ ( $ x : expr ) , * ) => { ... };
    ( $ ( $ x : expr , ) * ) => { ... };
}

Creates a Vec containing the arguments.

vec! allows Vecs to be defined with the same syntax as array expressions. There are two forms of this macro:

  • Create a Vec containing a given list of elements:
let v = vec![1, 2, 3];
assert_eq!(v[0], 1);
assert_eq!(v[1], 2);
assert_eq!(v[2], 3);
  • Create a Vec from a given element and size:
let v = vec![1; 3];
assert_eq!(v, [1, 1, 1]);

Note that unlike array expressions this syntax supports all elements which implement Clone and the number of elements doesn't have to be a constant.

This will use clone to duplicate an expression, so one should be careful using this with types having a nonstandard Clone implementation. For example, vec![Rc::new(1); 5] will create a vector of five references to the same boxed integer value, not five references pointing to independently boxed integers.

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/macro.vec.html