PHP Manual: Gets the registered iterator instances

public array MultipleIterator::key()

Get the registered iterator instances key() result.

Warning

This function is currently not documented; only its argument list is available.

This function has no parameters.

An array of all registered iterator instances.

A RuntimeException if the iterator is invalid (as of PHP 8.1.0), or mode MIT_NEED_ALL is set, and at least one attached iterator is not valid.

Calling this method from foreach triggers warning "Illegal type returned".

Version	Description
8.1.0	A RuntimeException is now thrown if MultipleIterator::key is called on an invalid iterator. Previously, `false` was returned.

MultipleIterator::key