PHP uniqid() produces a time-based identifier string with optional prefix and entropy suffix. The examples below show how the call behaves, where it is useful, and which limitations matter.
What Is uniqid() in PHP?
Produces a time-based identifier string with optional prefix and entropy suffix.
Its call structure is:
uniqid([$prefix], [$more_entropy])The arguments identify the values or resources passed to uniqid(). Read the examples with attention to the type of each supplied argument and to whether the function modifies its input or returns a separate result.
Example 1: Basic Usage
This example introduces uniqid with a direct call and a small, readable input.
<?php
echo uniqid("job_");Produces a time-based identifier string with optional prefix and entropy suffix. Values are predictable and not suitable for secrets or security tokens.
Example 2: Another Behavior or Input
Compare this input with the previous example: changing the data or option can affect how uniqid behaves.
<?php
echo uniqid("", true);The changed input illustrates why output may differ with the chosen values or environment. Values are predictable and not suitable for secrets or security tokens.
Practical Example: Using the Feature
The following example incorporates uniqid into a workflow. Values such as paths, connection handles and configuration options must come from trusted application settings.
<?php
$publicLabel = uniqid("batch_"); echo $publicLabel; // Not a security token.In a real application, check each operation result, validate values before use and clean up acquired resources. Values are predictable and not suitable for secrets or security tokens.
Important Behavior and Edge Cases
- Purpose: Produces a time-based identifier string with optional prefix and entropy suffix.
- Key limitation: Values are predictable and not suitable for secrets or security tokens.
- Failure handling: Check return values and handle invalid inputs and unavailable operating-system or extension features where relevant.
Comparison With Related Functions
| Function or Approach | Best Fit |
|---|---|
uniqid() | Produces a time-based identifier string with optional prefix and entropy suffix. |
bin2hex(random_bytes(...)) | Produces unpredictable random identifiers suitable for secrets when generated with enough bytes; uniqid() does not. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Values are predictable and not suitable for secrets or security tokens. | The correct approach depends on this behavior: Values are predictable and not suitable for secrets or security tokens. |
| Ignoring errors or cleanup after the operation. | Validate inputs and check each result; close files, restore settings or release resources when the operation requires it. |
Key Takeaways
- Produces a time-based identifier string with optional prefix and entropy suffix.
- Values are predictable and not suitable for secrets or security tokens.
- Use the examples as starting points, and adapt environmental paths, resources and permissions rather than assuming fixed results.
uniqid is useful when its specific behavior fits the problem. The safest implementations combine the correct API with input validation, error checking and resource cleanup.