PHP user_error() alias of trigger_error() for emitting a user-level error. The examples below show how the call behaves, where it is useful, and which limitations matter.
What Is user_error() in PHP?
Alias of trigger_error() for emitting a user-level error.
Its call structure is:
user_error($message, [$error_level])The arguments identify the values or resources passed to user_error(). 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 user_error with a direct call and a small, readable input.
<?php
user_error("Demo warning", E_USER_WARNING);Alias of trigger_error() for emitting a user-level error. This is not a replacement for exception-based application error handling.
Example 2: Another Behavior or Input
Compare this input with the previous example: changing the data or option can affect how user_error behaves.
<?php
user_error("Old method", E_USER_DEPRECATED);The changed input illustrates why output may differ with the chosen values or environment. This is not a replacement for exception-based application error handling.
Practical Example: Using the Feature
The following example incorporates user_error into a workflow. Values such as paths, connection handles and configuration options must come from trusted application settings.
<?php
function checkLevel(int $level): bool { if ($level > 10) { user_error("Level too high", E_USER_WARNING); return false; } return true; } var_dump(checkLevel(5));In a real application, check each operation result, validate values before use and clean up acquired resources. This is not a replacement for exception-based application error handling.
Important Behavior and Edge Cases
- Purpose: Alias of trigger_error() for emitting a user-level error.
- Key limitation: This is not a replacement for exception-based application error handling.
- 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 |
|---|---|
user_error() | Alias of trigger_error() for emitting a user-level error. |
trigger_error() | Canonical function for emitting user-level errors; user_error() is an alias. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| This is not a replacement for exception-based application error handling. | The correct approach depends on this behavior: This is not a replacement for exception-based application error handling. |
| 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
- Alias of trigger_error() for emitting a user-level error.
- This is not a replacement for exception-based application error handling.
- Use the examples as starting points, and adapt environmental paths, resources and permissions rather than assuming fixed results.
user_error is useful when its specific behavior fits the problem. The safest implementations combine the correct API with input validation, error checking and resource cleanup.