Traverse and Print

Walk from the head pointer to null, visiting each node exactly once without random indexing.

Algorithm

The replay labels nodes by value, such as node(20), and never exposes object identity or memory addresses. This PHP DSA implementation uses the same small chain as the rest of the DSA track.

Basic Implementation

basic.php

<?php
class Node {
    public int $value;
    public ?Node $next;
    public function __construct(int $value, ?Node $next = null) {
        $this->value = $value;
        $this->next = $next;
    }
}
function render_chain(?Node $head): string {
    $parts = [];
    $cursor = $head;
    while ($cursor !== null) {
        $parts[] = (string)$cursor->value;
        $cursor = $cursor->next;
    }
    return implode(" -> ", $parts) . " -> null";
}
$head = new Node(10, new Node(20, new Node(30)));
echo render_chain($head) . PHP_EOL;

Complexity

Time: O(n)
Space: O(1)

Implementation notes

Keep the explicit node and pointer/reference operations; array shortcuts hide the linked-list state this lesson is meant to replay.
The final output prints the chain in a deterministic a -> b -> null form for cross-language comparison.

cursor A cursor reference names the node currently being visited.

null stop Traversal ends when the cursor reaches the null marker.