PHP SplHeap::top() Method: Usage and Examples

Peeks at the highest-priority element without removing it.

The examples focus on the operation itself, including the important distinction: extract returns and removes the root.

What It Does

Use the examples below to observe the behavior on a small dataset before extending it to application code.

Syntax and Return Value

SplHeap::top()

The displayed signature describes the API or identifies any correction or optional dependency. When a parameter is optional, supply it only when the task requires it.

Example 1: Basic Use

SplMaxHeap is used because the abstract SplHeap cannot be instantiated. The top call is shown on a small, inspectable dataset.

<?php
$heap = new SplMaxHeap();
$heap->insert(4);
$heap->insert(12);
$heap->insert(7);
echo json_encode($heap->top());

Output from a successful local PHP 8.4 run:

12

Example 2: Checking Behavior

SplMaxHeap is used because the abstract SplHeap cannot be instantiated. The top call is shown on a small, inspectable dataset.

<?php
$heap = new SplMaxHeap();
$heap->insert(2);
$heap->insert(9);
$heap->insert(5);
$heap->insert(1);
echo json_encode($heap->top());

Output from a successful local PHP 8.4 run:

9

Example 3: Practical Example

SplMaxHeap is used because the abstract SplHeap cannot be instantiated. The top call is shown on a small, inspectable dataset.

<?php
$heap = new SplMaxHeap();
$heap->insert(19);
$heap->insert(3);
$heap->insert(11);
echo json_encode($heap->top());

Output from a successful local PHP 8.4 run:

19

Important Behavior and Edge Cases

An empty heap raises RuntimeException.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Peeks at the highest-priority element without removing it.
• An empty heap raises RuntimeException.
• extract returns and removes the root.

Use SplHeap::top when its documented behavior matches the problem. Test the relevant edge cases in your own runtime before deploying it.