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:

fn main() { let v = vec![1, 2, 3]; assert_eq!(v[0], 1); assert_eq!(v[1], 2); assert_eq!(v[2], 3); }

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:

fn main() { let v = vec![1; 3]; assert_eq!(v, [1, 1, 1]); }

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.