Question

Possible Duplicate:
PHP Insert at particular index

Is it possible to to insert in the middle of a linked list in php. If yes, can someone please provide me with the code of the function that implements it?

Answer 1

Yes it is possible.

function insertIntoMiddle($LinkedList, $NewItem)
{
    // we will use current as a pointer to the current position in our list
    // if we arrive at the middle, we insert the $NewItem
    $currentIndex = 0;
    $currentItem = $LinkedList->getFirstItem();

    // calculate the middle of your list
    $middleIndex = floor($LinkedList->getLength() / 2);

    // Loop over the list until you get the item in the middle
    while (++$currentIndex < $middleIndex)
    {
        $currentItem = $currentItem->getNextItem();
    }

    // insert the $NewItem between $currentItem and the next
    $NewItem->setNextItem($currentItem->getNextItem());
    $currentItem->setNextItem($NewItem);

    // also setPreviousItem() if you have linked your list both ways
}

This is of course pseudo-code as you didn’t provide any example code.