# std::vec!
[−]

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

Creates a `Vec`

containing the arguments.

`vec!`

allows `Vec`

s 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.