The PHP EmptyIterator::next API performs a focused operation on an object or value. The examples below show its effect on actual data.
Advances to the next iteration position; an exhausted iterator has no current entry.
What Is EmptyIterator::next in PHP?
Advances to the next iteration position; an exhausted iterator has no current entry.
Syntax:
EmptyIterator::next()This operation has no parameters.
Return type declared by PHP: mixed / not explicitly declared. The value or side effect is demonstrated in the examples below.
Example 1: Basic Usage
This example uses a small input to make the main behavior visible.
<?php
$emptyIterator = new EmptyIterator();
$emptyIterator->next();
var_dump($emptyIterator->valid());Output:
bool(false)Advances to the next iteration position; an exhausted iterator has no current entry.
Example 2: A Different Input
A different set of values shows the same operation in another situation.
<?php
$emptyIterator = new EmptyIterator();
// Iterator methods do not produce elements from an empty sequence.
$emptyIterator->next();
var_dump($emptyIterator->valid());
var_dump(iterator_count(new EmptyIterator()));Output:
bool(false)
int(0)An empty iterator has no value or key; accessing either throws BadMethodCallException.
Practical Example: Applying the Feature
This example shows an application-style use of the feature, with its surrounding setup visible.
<?php
$emptyIterator = new EmptyIterator();
$emptyIterator->rewind();
$emptyIterator->next();
foreach ($emptyIterator as $item) { echo $item; }
echo "Completed without entries";Output:
Completed without entriesThe code is shown for learning. Adjust the class names, inputs and error handling to suit your application.
Important Behavior and Edge Cases
- An empty iterator has no value or key; accessing either throws BadMethodCallException.
- Advances to the next iteration position; an exhausted iterator has no current entry.
- Observe differences in empty inputs, invalid states and optional extension availability where relevant.
Comparison With Related Approaches
| Approach | Important Difference |
|---|---|
EmptyIterator::next | Advances to the next iteration position; an exhausted iterator has no current entry. |
| ArrayIterator | An empty ArrayIterator also yields no values, but its current() and key() behavior is not the same as EmptyIterator exceptions. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
Ignoring the documented state or precondition of EmptyIterator::next | An empty iterator has no value or key; accessing either throws BadMethodCallException. |
| Expecting a different type of result | Read the declared return type and distinguish returned values from changes to the source object. |
| Assuming a related API works identically | An empty ArrayIterator also yields no values, but its current() and key() behavior is not the same as EmptyIterator exceptions. |
Key Takeaways
- Advances to the next iteration position; an exhausted iterator has no current entry.
- An empty iterator has no value or key; accessing either throws BadMethodCallException.
- Use the example that matches the values, runtime version and dependencies in your application.
EmptyIterator::next is useful when its behavior matches the data structure and lifecycle of your PHP application. Choose it with a clear understanding of its preconditions and returned values.