rewinddir() resets an open directory handle to the beginning of its listing. This guide explains the function with focused examples and the decisions that matter in real applications.
What Is rewinddir() in PHP?
Resets an open directory handle to the beginning of its listing.
A typical call looks like this:
<?php
rewinddir([$dir_handle]);
The input arguments shown in the call identify the relevant connection, resource, value, path or configuration for the operation. Pay attention to argument order and to the return value demonstrated below.
Example 1: Basic Usage
This first example uses rewinddir() directly to demonstrate its basic purpose.
<?php
$directory = opendir(__DIR__); readdir($directory); rewinddir($directory); echo readdir($directory); closedir($directory);
The returned value illustrates resets an open directory handle to the beginning of its listing. Directory contents may change between reads.
Example 2: A Different Input or Option
The next example changes the input or option, showing another supported use of rewinddir().
<?php
$directory = opendir(__DIR__); while (readdir($directory) !== false) {} rewinddir($directory); var_dump(readdir($directory)); closedir($directory);
The returned value illustrates resets an open directory handle to the beginning of its listing. Directory contents may change between reads.
Practical Example: Applying the Function
In application code, rewinddir() belongs in a controlled workflow with input validation, a checked result and cleanup where needed.
<?php
$directory = opendir(__DIR__); $first = readdir($directory); rewinddir($directory); $again = readdir($directory); echo $first === $again ? "Reset succeeded" : "Listing changed"; closedir($directory);
The returned value illustrates resets an open directory handle to the beginning of its listing. Directory contents may change between reads.
Important Behavior and Edge Cases
- Main behavior: Resets an open directory handle to the beginning of its listing.
- Important limitation: Directory contents may change between reads.
- Requirements: Check the runtime, file permissions and operating system when results depend on the environment.
Comparison With Related Functions
| Function or Approach | When to Use It |
|---|---|
rewinddir() | Resets an open directory handle to the beginning of its listing. |
readdir | Reads the next name from an open directory handle. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
Ignoring the specific limits or preconditions of rewinddir(). | Directory contents may change between reads. |
| Assuming every environment produces the same result. | Check the runtime, file permissions and operating system when results depend on the environment. |
Key Takeaways
- Resets an open directory handle to the beginning of its listing.
- Directory contents may change between reads.
- Check the runtime, file permissions and operating system when results depend on the environment.
Use rewinddir() when its behavior matches your task, and verify the relevant return value before taking further action. The output depends on the local configuration when it uses resources, files or an interactive terminal.