'@' symbol in php, e.g. '@$name[1]'?

Question

All,

What is the signification of the '@' symbol in PHP? For example, what does it mean in this statement:

$sd = (@$argv[1]) ? getdate(strtotime($argv[1])) : getdate();

I understand the ternary operator '?', but I have no idea what the '@' means...

The code is sample code from the (very good!) cs75.net Harvard extension course.

Thanks,

JDelage

Dupe, though the SO search isn't exactly helpful with these symbols. http://stackoverflow.com/questions/2279289/what-is-the-meaning-of-in-php-closed — Annika Backstrom, Jun 18 '10 at 12:59
Darn, I searched for it, but couldn't find anything. The answers are better here, IMHO. — JDelage, Jun 18 '10 at 13:54

Russell Dias · Accepted Answer · 2010-06-18T12:48:25.717

The @ symbol suppresses any errors which may be produced in the course of the function (or expression).

PHP supports one error control operator: the at sign (@). When prepended to an expression in PHP, any error messages that might be generated by that expression will be ignored.

Error suppression should be avoided if possible as it doesn't just suppress the error that you are trying to stop, but will also suppress errors that you didn't predict would ever occur. This will make debugging a nightmare.

MiffTheFox · Answer 2 · 2010-06-18T22:04:38.090

The @ supressess any error messages from the expression, that is, if E_NOTICE is set

$argv = Array("Only one object.");
if ($argv[1]) { print "Argv[1] set"; }

would cause an warning, but

$argv = Array("Only one object.");
if (@$argv[1]) { print "Argv[1] set"; }

would simply not print anything.

Keep in mind though, that it's a much better practice to use

if (!empty($var)) { print "Argv[1] is set and non-false."; }

instead.

score 1 · Answer 3 · answered Jun 18 '10 at 12:43

1

It's the solution for the programmer who can't be arsed checking if $argv[1] is defined and doesn't want to see a warning telling him how lazy he is. Also known as error suppression.

answered Jun 18 '10 at 12:43

Matteo Riva

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Or the *lazy* answerer that doesn't mention it should be replaced with `isset($argv[1])` or `!empty($argv[1])` ;) – gnarf Jun 18 '10 at 12:46
The OP only asked what it is :) – Matteo Riva Jun 18 '10 at 12:48

score 1 · Answer 4 · answered Jun 18 '10 at 12:56

Others have explained that @ suppresses error messages. Fun fact from Ilia Alshanetsky's talk on "PHP and Performance":

The error blocking operator is the most expensive character in PHP’s alphabet. This seemingly innocuous operator actually performs fairly intensive operations in the background:

$old = ini_set("error_reporting", 0);
action();
ini_set("error_reporting", $old);

'@' symbol in php, e.g. '@$name[1]'?

4 Answers4