PHP-递归二叉树

Question

I've been having some fun with PHP trying to explore its potentials so I tried to see if I can implement a binary tree structure. Here is the code:

class Node{
    public $leftNode;
    public $rightNode;
    public $value;
    public function Node($value){
        $this->value = $value;
    }
}

class binTree{
    public function inserter(Node $node, $value){
        if($value < $node->value){
            if($node->leftNode != null){
                inserter($node, $value);
            }
            else{
                $node->leftNode = new Node($value);
            }
        }
        else if($value > $node->value){
            if($node->rightNode != null){
                inserter($node, $value);
            }
            else{
                $node->rightNode = new Node($value);
            }
        }
    }   
}

Now for some reason, when I try to call the inserter function within itself (ie inserter ($node, $value), I get this error: Fatal error: Call to undefined function inserter(). So I tried referencing it via $this and even binTree:: with no luck. I get Fatal error: Using $this when not in object context and Fatal error: Allowed memory size of 134217728 bytes exhausted errors respectively. Can anyone explain what is happening?

Answer 1

i suspect your problem is the following:

php constructor works this way

public function __construct ()
{

}

(vs C# like syntax that you are using)

Answer 2

Try this:

<?php
class Node{
    public $leftNode;
    public $rightNode;
    public $value;

    // changed the constructor name from "Node" to "__construct"
    public function __construct($value){
        $this->value = $value;
    }
}

class binTree{
    public function inserter(Node $node, $value){
        if($value < $node->value){
            if($node->leftNode != null){
                // added "$this->"
                $this->inserter($node, $value);
            }
            else{
                $node->leftNode = new Node($value);
            }
        }
        else if($value > $node->value){
            if($node->rightNode != null){
                // added "$this->"
                $this->inserter($node, $value);
            }
            else{
                $node->rightNode = new Node($value);
            }
        }
    }
}

$binTree = new binTree();
$binTree->inserter(new Node('foo'), 'bar');