(PHP 5 >= 5.5.0, PHP 7, PHP 8)
SplDoublyLinkedList::add — Add/insert a new value at the specified index
Insert the value value at the
specified index, shuffling the
previous value at that index (and all subsequent values)
up through the list.
indexThe index where the new value is to be inserted.
value
The new value for the index.
No value is returned.
Throws OutOfRangeException when
index is out of bounds or when
index cannot be parsed as an integer.