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

Tests whether there are entries available for iteration.

The examples focus on the operation itself, including the important distinction: isEmpty tests the same collection state but not an iterator position.

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::valid()

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 valid call is shown on a small, inspectable dataset.

<?php
$heap = new SplMaxHeap();
$heap->insert(4);
$heap->insert(12);
$heap->insert(7);
$heap->rewind();
echo $heap->valid() ? "has item" : "finished";

Output from a successful local PHP 8.4 run:

has item

Example 2: Checking Behavior

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

<?php
$heap = new SplMaxHeap();
$heap->insert(2);
$heap->insert(9);
$heap->insert(5);
$heap->insert(1);
$heap->rewind();
echo $heap->valid() ? "has item" : "finished";

Output from a successful local PHP 8.4 run:

has item

Example 3: Practical Example

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

<?php
$heap = new SplMaxHeap();
$heap->insert(19);
$heap->insert(3);
$heap->insert(11);
$heap->rewind();
echo $heap->valid() ? "has item" : "finished";

Output from a successful local PHP 8.4 run:

has item

Important Behavior and Edge Cases

Because iteration extracts entries, the result may change while traversing.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Tests whether there are entries available for iteration.
• Because iteration extracts entries, the result may change while traversing.
• isEmpty tests the same collection state but not an iterator position.

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