collections::vec - Rust
Description: API documentation for the Rust `vec` macro in crate `collections`.
Keywords: rust, rustlang, rust-lang, vec

# Macro collections::vec 1.0.0 [−] [src]

    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);Run

- Create a `Vec` from a given element and size:

    let v = vec![1; 3];
    assert_eq!(v, [1, 1, 1]);Run

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.

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