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

# Macro 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);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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