Implementing a linked list with PHP

For reference, the code can also continue to be polished

and put it on my github: https://github.com/hheedat/demo/blob/master/learn_php/58_linked_list.php

<?phpclass node{public $data; public $next;}    Class linkedlist{private $_head;    Private $_tail;    Private $_length;        function init () {$this->_head = $this->_tail = null;    $this->_length = 0;        } function Makenode ($data) {$node = new node ();        $node->data = $data;    return $node;         The function push ($node) {if ($this->_head = = NULL) {$this->_head = $this->_tail = $node;            } else {$this->_tail->next = $node;        $this->_tail = $node;    } + $this->_length;        } function Pop () {if ($this->_head = = null) {return false;            } elseif ($this->_length > 1) {$node = $this->makenode ($this->_tail->data);            $secondTail = $this->_head;            while ($secondTail->next! = $this->_tail) {$secondTail = $secondTail->next; } $this_tail = $secondTail;            $this->_tail->next = null;            --$this->_length;        return $node;            } elseif ($this->_length = = 1) {$node = $this->makenode ($this->_tail->data);            $this->_head = $this->_tail = null;            --$this->_length;        return $node; }} function Unshift ($node) {if ($this->_head = = null) {$this->_head = $this->_tail        = $node;            } else {$node->next = $this->_head;        $this->_head = $node;    } + $this->_length;        } function Shift () {if ($this->_head = = null) {return false;            } else {$node = $this->makenode ($this->_head->data);            $this->_head = $this->_head->next;            --$this->_length;        return $node;        }} function Map ($func) {$node = $this->_head;        $index = 0; WhIle ($node! = null) {$func ($node->data, $index + +);        $node = $node->next; }} function reverse () {if ($this->_length > 1) {$this->_tail = $p = $this->_head            ;            if ($p! = null) $q = $p->next;            if ($q! = null) $r = $q->next;                while ($q! = null) {$q->next = $p;                $p = $q;                $q = $r;            if ($r! = null) $r = $r->next;            } $this->_head = $p;        $this->_tail->next = null;    }} function GetLength () {return $this->_length;  }}//test code$linkedlist = new LinkedList (); for ($i = 0; $i < 5; + + $i) {$node = $linkedList->makenode (($i + 1).    ' Apple ');    $linkedList->push ($node); $node = $linkedList->makenode (($i + 1).    ' Banana '); $linkedList->unshift ($node);} echo "Linked list length is". $linkedList->getlength (). "\ n"; $linkedList->map(Function ($val, $index) {echo "index is: $index \ t value is: $val \ n";}); echo "Shift, Value is:". $linkedList->shift ()->data. "\ n"; echo "Pop, value is:". $linkedList->pop ()->data. "\ n"; echo "Shift, Value is:". $linkedList->shift ()->data. "\ n"; echo "Pop, value is:". $linkedList->pop ()->data. "\ n"; echo "linked list length is". $linkedList->getlength (). "\ n"; $linkedList->map (function ($val, $index) {echo "index is: $index \ t value is: $val \ n";}); $linkedList->reverse (); echo "Linked list length is". $linkedList->getlength (). "After reverse\n"; $linkedList->map (function ($val, $index) {echo ' index is: $index \ t value is: $val \ n ";});

The expected output is:

LinkedListLength is 10Index is: 0 Value Is:5Bananaindex is: 1 Value Is:4Bananaindex is: 2 Value Is:3Bananaindex is: 3 Value Is:2Bananaindex is: 4 Value Is:1Bananaindex is: 5 Value Is:1Appleindex is: 6 Value Is:2Appleindex is: 7 Value Is:3Appleindex is: 8 Value Is:4Appleindex is: 9 Value Is:5Appleshift, Value Is:5Bananapop, Value Is:5Appleshift, Value Is:4Bananapop, Value Is:4applelinkedListLength is 6Index is: 0 Value Is:3Bananaindex is: 1 Value Is:2Bananaindex is: 2 Value Is:1Bananaindex is: 3 Value Is:1Appleindex is: 4 Value Is:2Appleindex is: 5 Value Is:3applelinkedListLength is 6After Reverseindex is: 0 Value Is:3Appleindex is: 1 Value Is:2Appleindex is: 2 Value Is:1Appleindex is: 3 Value Is:1Bananaindex is: 4 Value Is:2Bananaindex is: 5 Value Is:3 Banana

Implementing a linked list with PHP