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

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

Example

A simple example of a custom error handler:

php<?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:

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

Example

Handling only specific error types:

php<?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:

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

Example

Restoring the standard error handler:

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