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key

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.

( excerpt from http://php.net/manual/en/iterator.key.php )

public function key(): mixed;

Returns the key of the current element.

Returns​

  • mixed - Returns scalar on success, or NULL on failure.