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add

Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Appends a value to the end of the current Vector, assigning it the next available integer key

public function add(
  Tv $value,
): Vector<Tv>;

If you want to overwrite the value for an existing key, use set().

$vec->add($v) is semantically equivalent to $vec[] = $v (except that add() returns the current Vector).

Future changes made to the current Vector ARE reflected in the returned Vector, and vice-versa.

If $v is an object, future changes to the added element ARE reflected in $v, and vice versa.

Parameters​

  • Tv $value

Returns​

Examples​

The following example adds a single value to the Vector $v and also adds multiple values to $v through chaining. Since Vector::add() returns a shallow copy of $v itself, you can chain a bunch of add() calls together, and that will add all those values to $v.

$v = Vector {};

$v->add('red');
\var_dump($v);

// Vector::add returns the Vector so it can be chained
$v->add('green')
  ->add('blue')
  ->add('yellow');
\var_dump($v);