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firstKey

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.

Returns the first key in the current Pair

public function firstKey(): int;

The return will always be 0 since a Pair only has two keys, 0 and 1.

Returns​

  • int - 0

Examples​

$p = Pair {'foo', -1.5};
\var_dump($p->firstKey());