Which Fires First? Error Handler or Shutdown Function

April 24th, 2008 by Aaron

I was working on writing a shutdown function for a PHP 4 script and noticed some odd behavior when I was getting errors (no way! I program and get errors? Who knew!?) At any rate, when I would handle my error with my custom function, I noticed the shutdown function was still executing after the error function. (Or when it was a Fatal error, the error was shown to the screen but the shutdown function was still ran…)

This got me to thinking about handling error redirection pages and sending messages on fatal errors in PHP4 (you’ll remember that a fatal error won’t execute the error handler, and therefore most of our custom code to make a nice ‘message’ won’t execute). But anyway, I digress.

I’m using PHP5.2 - this is the code I used to test:

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<?php
function error_function() {
  print 'error function';
}
function shutdown_function() {
  print 'shutdown function';
}
set_error_handler('error_function');
register_shutdown_function('shutdown_function');
print 1/0;
?>

So, as you can tell, the error handler happens FIRST and then the shutdown function

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Tags: PHP

This entry was posted on Thursday, April 24th, 2008 at 5:50 pm and is filed under PHP. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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