The set_error_handler Function

The set_error_handler function sets a user-defined error handler. The first parameter is a callback function that will be called when an error occurs. The second optional parameter can specify the types of errors that the handler should intercept.

Syntax

set_error_handler(callable $error_handler, int $error_types = E_ALL | E_STRICT);

Example

A simple example of a custom error handler:

<?php
	function customError($errno, $errstr, $errfile, $errline) {
		echo "Error [$errno]: $errstr in $errfile on line $errline";
	}
	
	set_error_handler("customError");
	
	echo $undefinedVar;
?>

Code execution result:

Error [8]: Undefined variable: undefinedVar in /path/to/file.php on line 7

Example

Handling only specific error types:

<?php
	function warningHandler($errno, $errstr) {
		if ($errno === E_WARNING) {
			echo "Warning captured: $errstr";
		}
	}
	
	set_error_handler("warningHandler", E_WARNING);
	
	strpos(); // Will cause a warning
?>

Code execution result:

Warning captured: strpos() expects at least 2 parameters, 0 given

Example

Restoring the standard error handler:

<?php
	set_error_handler(null); // Restore to the standard handler
?>