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

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

Allocates enough memory for a required capacity.

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\Map::allocate example

<?php
$map = new \Ds\Map();
var_dump($map->capacity());

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

上の例の出力は、たとえば以下のようになります。

int(16)
int(128)