PHP – how to catch errors using set_error_handler

PHP set_error_handler can catch various type of php errors in a specific portion of the code. To restore the previous error hander one can call restore_error_handler function. Here is a sample code snippet and its outcome.

<?php
function my_error_handler ($errno, $errstr, $errfile, $errline) {
  echo "errstr=$errstr";
  // return true to bypass  standard php error handler
  return true;
}
set_error_handler('my_error_handler', E_ALL | E_STRICT);
// this will cause warning due to bad regex
$ret = preg_match("abc", "abcdef");
restore_error_handler();
?>

errstr=preg_match(): Delimiter must not be alphanumeric, backslash, or NUL

Few points to note

1. Returning true from error handler will bypass php standard error handler.
2. restore_error_handler will restore previous hander. In our case default php error handler.
3. It is pretty useful in case you are executing code obtained from thord party.