[RESOLVED] the @

dougal85

I've often seen things like;

<?php

$var = @$_GET['something'];

What does the @ do?

It's one of these annoying things thats impossible to search for...

NogDog

Error control operators

Please use it with caution, and not as a way to hide sloppy coding (as often seems to be the case in some of the code where I've seen it used).

bradgrafelman

dougal85 wrote:
It's one of these annoying things thats impossible to search for...

Hehe.. you're reminding me of the time I first saw it used... :p

dougal85

It's funny actually, I've been meaning to ask for a while. I've been doing PHP for about 2 years now and every time I've seen it in a example... I've deleted it because i didn't know what it did and everything always worked.

I understand now what it does... but i cant imagine ever wanting to use it! It seems like a strange idea, I'd rather handle my errors. I hate it when i don't know whats going on with my code.

Is there a simple example that would demonstrate its usefulness?

The only thing i can think of is, in my footers i sometimes do a mysql_close just to make sure i don't forget, i guess i could use it on that so that if there is nothing to close it wont tell me.

bradgrafelman

Here's one of the most common (mis?)uses of it:

<?php

$var = @$_GET['something'];

?>

Look familiar? :p

Seriously though, when referencing $GET, $POST, etc. ... people find it easier to use the above syntax instead of a more proper way:

$var = (isset($_GET['something'] ? $_GET['something'] : '');

NogDog

The main reason I use it (occasionally) is for situations where I don't want PHP to output standard error messages that might screw up the output of the page or, more importantly, to prevent malicious users from gaining too much info about the site structure. For instance:

$fh = @fopen('/home/username/datfiles/file.txt');
if($fh == FALSE)
{
   echo "<p class='error'>Sorry, there was an error accessing the project data</p>\n";
}
else
{
  // continue processing data from the file...
}

So in this case, the user would only see a generic error message rather than something to the effect that PHP was unable to open the file '/home/username/datfiles/file.txt'. But the main thing to remember is that if you're going to suppress error messages, then it becomes your responsibility to make sure you handle any errors in an appropriate manner.

bradgrafelman

All good points, which usually point towards developing your own error handler and using [man]set_error_handler/man.

Weedpacket

It's also one of the uglier performance hits I've just found - for the "$var = @$_GET['something']; " example it's something like 60 times slower than testing it properly. Or some ridiculous number like that.

dougal85

bradgrafelman wrote:
All good points, which usually point towards developing your own error handler and using [man]set_error_handler/man.

I have been using the error handler for a while now, its really useful to preserve the site's look. I also use it to log specific errors too.

You guys know so much... Thanks again!

laserlight

It's also one of the uglier performance hits I've just found - for the "$var = @$_GET['something']; " example it's something like 60 times slower than testing it properly. Or some ridiculous number like that.

I did some tests, and it looks closer to the region of twice to four times as long. Still rather ridiculous, I suppose, for something that is poor practice to begin with 🙂