PHP マニュアル: Allocates enough memory for a required capacity

public void Ds\Deque::allocate(int $capacity)

Ensures that enough memory is allocated for a required capacity. This removes the need to reallocate the internal as values are added.

capacity: The number of values for which capacity should be allocated.

注意:
Capacity will stay the same if this value is less than or equal to the current capacity.

注意:
Capacity will always be rounded up to the nearest power of 2.

値を返しません。

例1 Ds\Deque::allocate example

<?php
$deque = new \Ds\Deque();
var_dump($deque->capacity());

$deque->allocate(100);
var_dump($deque->capacity());
?>

上の例の出力は、たとえば以下のようになります。

int(8)
int(128)