The trigger_error Function

The trigger_error function generates a custom error message. Its first parameter is the message text, and the second is the error level (default is E_USER_NOTICE). The function is useful for debugging and creating your own error handling system.

Syntax

trigger_error(message, error_level);

Example

Let's generate a simple notice:

<?php
	trigger_error("This is a notice message");
?>

Code execution result:

Notice: This is a notice message in file.php on line 2

Example

Let's generate a custom warning:

<?php
	trigger_error("Invalid value entered", E_USER_WARNING);
?>

Code execution result:

Warning: Invalid value entered in file.php on line 2

Example

Let's generate a fatal error:

<?php
	trigger_error("Critical system error", E_USER_ERROR);
?>

Code execution result:

Fatal error: Critical system error in file.php on line 2

Example

Usage in a conditional structure:

<?php
	$age = -5;
	if ($age < 0) {
		trigger_error("Age cannot be negative", E_USER_WARNING);
	}
?>

Code execution result:

Warning: Age cannot be negative in file.php on line 4