# Module alloc::vec

1.0.0 · source ·
Expand description

A contiguous growable array type with heap-allocated contents, written `Vec<T>`.

Vectors have O(1) indexing, amortized O(1) push (to the end) and O(1) pop (from the end).

Vectors ensure they never allocate more than `isize::MAX` bytes.

## Examples

You can explicitly create a `Vec` with `Vec::new`:

    let v: Vec<i32> = Vec::new();

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…or by using the `vec!` macro:

    let v: Vec<i32> = vec![];

    let v = vec![1, 2, 3, 4, 5];

    let v = vec![0; 10]; // ten zeroes

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You can `push` values onto the end of a vector (which will grow the vector as needed):

    let mut v = vec![1, 2];

    v.push(3);

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Popping values works in much the same way:

    let mut v = vec![1, 2];

    let two = v.pop();

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Vectors also support indexing (through the `Index` and `IndexMut` traits):

    let mut v = vec![1, 2, 3];
    let three = v[2];
    v[1] = v[1] + 5;

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## Structs

- ExtractIf Experimental
  An iterator which uses a closure to determine if an element should be removed.
- Drain
  A draining iterator for `Vec<T>`.
- IntoIter
  An iterator that moves out of a vector.
- Splice
  A splicing iterator for `Vec`.
- Vec
  A contiguous growable array type, written as `Vec<T>`, short for ‘vector’.