Error handling in PHP helps you detect, manage, and debug issues in your code efficiently.
🔴 1. Error Types in PHP
PHP has different types of errors:
✅ Common Error Types:
| Error Type | Description |
|---|---|
| E_NOTICE | Minor issues (e.g., undefined variable) |
| E_WARNING | Non-fatal errors (script continues) |
| E_ERROR | Fatal error (script stops) |
| E_PARSE | Syntax errors |
| E_DEPRECATED | Using outdated features |
| E_ALL | All errors |
📌 Example:
echo $name; // Undefined variable → Notice🟡 2. Displaying Errors
Enable error reporting:
error_reporting(E_ALL);
ini_set('display_errors', 1);Disable in production:
ini_set('display_errors', 0);🟢 3. try-catch Blocks (Exception Handling)
Used to handle runtime errors (exceptions).
📌 Basic Example:
try {
$num = 10 / 0;
} catch (Throwable $e) {
echo "Error: " . $e->getMessage();
}📌 Custom Exception:
function checkAge($age) {
if ($age < 18) {
throw new Exception("Underage!");
}
return "Access granted";
}try {
echo checkAge(16);
} catch (Exception $e) {
echo $e->getMessage();
}🔵 4. Custom Error Handling
You can create your own error handler.
📌 Example:
function customError($errno, $errstr) {
echo "Error [$errno]: $errstr";
}set_error_handler("customError");// Trigger error
echo $test; // undefined variable🟣 5. Trigger Custom Errors
trigger_error("Something went wrong!", E_USER_WARNING);🟠 6. Debugging Techniques
✅ 1. Print Variables
print_r($data);
var_dump($data);✅ 2. Use die() / exit()
die("Stop here");✅ 3. Logging Errors
error_log("This is an error message", 3, "error.log");✅ 4. Stack Trace
try {
throw new Exception("Test error");
} catch (Exception $e) {
echo $e->getTraceAsString();
}🔥 7. Best Practices (Important)
- ❌ Don’t show errors to users in production
- ✅ Log errors instead
- ✅ Use try-catch for critical operations
- ✅ Validate inputs properly
- ✅ Use custom error handlers for large apps
🚀 Real-World Example
try {
$conn = new mysqli("localhost", "root", "", "test"); if ($conn->connect_error) {
throw new Exception("Database connection failed");
} echo "Connected successfully";} catch (Exception $e) {
error_log($e->getMessage());
echo "Something went wrong. Please try later.";
}
