I cant figure out the diffrence between following two syntaxes

Question

while($rowForStateList  =   @mysql_fetch_array($resForStateList))

{
    $sid[$i]    =   $rowForStateList['state_auto_id'];

    $sname[$i]  =   $rowForStateList['state_name'];

    $spid[$i]   =   $rowForStateList['country_auto_id'];

    $i++;
}

AND

while($rowForStateList  =   mysql_fetch_array($resForStateList))

{
    $sid[$i]    =   $rowForStateList['state_auto_id'];

    $sname[$i]  =   $rowForStateList['state_name'];

    $spid[$i]   =   $rowForStateList['country_auto_id'];

    $i++;
}

The `@` sign is the difference. There is a question: What does this symbol means here on SO. — hakre, Aug 25 '11 at 08:23
possible duplicate of [Reference - What does this symbol mean in PHP?](http://stackoverflow.com/questions/3737139/reference-what-does-this-symbol-mean-in-php) — hakre, Aug 25 '11 at 08:24

J0HN · Accepted Answer · 2011-08-25T08:37:28.877

2

The difference is that @mysql_fetch_array in first code sample fetches the array suppressing any errors, while mysql_fetch_array do the same but not suppressing errors. Actually, the second one is more correct way.

The evil of using @ is in that it comlicates debugging a lot. With this suppression, in case of error you'll end up with empty arrays, so it will look just like query used to get $resForStateList have returned empty result. But, you actually might have broken query, refused database connection and whatever else. And with @ you will never know that something goes wrong.

So, don't use @. Instead, use error handling functions. And the best way is to check if something could cause error, e.g. mysql_query returns false in case of any error, so you might want to check it like

$result = nysql_query("qwerty");
if (!$result){
    echo mysql_error();
}

edited Aug 25 '11 at 08:37

answered Aug 25 '11 at 08:25

J0HN

26,063
5
54
85

+1 for saying that using @ is incorrect. You might want to add why though. – GordonM Aug 25 '11 at 08:27
So, would somebody explain why this post is downvoted? Am I wrong? :) – J0HN Aug 25 '11 at 08:42
@JOHN, you got me. Mine got downvoted too, I think someone got their panties in a twist over posts that said or implied that the @ operator wasn't a good idea. – GordonM Aug 25 '11 at 14:15

score 1 · Answer 2 · answered Aug 25 '11 at 08:23

1

The difference is that the former will mask any errors that occur in mysql_fetch_array(), making debugging more difficult.

answered Aug 25 '11 at 08:23

Ignacio Vazquez-Abrams

776,304
153
1,341
1,358

score 1 · Answer 3 · answered Aug 25 '11 at 08:26

1

The @ in the first version basically means "If this function triggers an error, just hide it, don't log or display it".

Don't ever use the @ error suppression operator! Not only does it make for a debugging nightmare, but it also harms application performance. Use error_reporting, log_errors and display_errors to set proper error message behaviour instead.

answered Aug 25 '11 at 08:26

GordonM

31,179
15
87
129

And someone appears to have downvoted this? Could you explain why? – GordonM Aug 25 '11 at 14:16

score 1 · Answer 4 · answered Aug 25 '11 at 08:29

1

Don't use the @ operator in this case. mysql_fetch_array will only throw an error if the resource is not valid. You should have checked this before, after you got this resource.

answered Aug 25 '11 at 08:29

GolezTrol

114,394
18
182
210

score 0 · Answer 5 · answered Aug 25 '11 at 08:24

0

The difference is the error reporting. If you set a @ before mysql_fetch_array, any errors will be ignored. see php errorcontrol

answered Aug 25 '11 at 08:24

Georg Leber

3,470
5
40
63

score 0 · Answer 6 · answered Aug 25 '11 at 08:24

0

the only difference is that the @ in front of the mysql_fetch_array in the first code will supress any error from being displayed on the screen.

answered Aug 25 '11 at 08:24

Christophe

4,798
5
41
83

score 0 · Answer 7 · answered Aug 25 '11 at 08:24

0

the first one suppresses errors: http://davidwalsh.name/suppress-php-errors-warnings

answered Aug 25 '11 at 08:24

Flask

4,966
1
20
39

score 0 · Answer 8 · answered Aug 25 '11 at 08:24

0

They are identical. The first mysql_fetch_array() will not produce error messages due to the suppression operator @.

answered Aug 25 '11 at 08:24

Linus Kleen

33,871
11
91
99

score 0 · Answer 9 · answered Aug 25 '11 at 08:24

0

The first one will silently ignore any error. The second one will display any error or exceptions thrown the mysql_fetch_array (for example, connection problem). The magic comes from the @ sign.

answered Aug 25 '11 at 08:24

Yanick Rochon

51,409
25
133
214

score 0 · Answer 10 · answered Aug 25 '11 at 08:25

0

@mysql_fetch_array($resForStateList)) doesn't show up any message in case of an error. That's all.

answered Aug 25 '11 at 08:25

HBublitz

670
4
6

score 0 · Answer 11 · answered Aug 25 '11 at 08:26

0

The @ is an operator thet suppresses errors. Your statement will not throw errors when the @ is added. You can read more here: http://thesmithfam.org/blog/2006/05/07/php-the-operator/

answered Aug 25 '11 at 08:26

Дамян Станчев

2,654
5
30
53

score 0 · Answer 12 · answered Aug 25 '11 at 08:57

When you prepend '@' to an expression, any error messages that might be generated will be ignored (ie. no error output will be generated). Anyway if the track_errors feature is enabled, any error message generated by the expression will be saved (and overwritten on each error) in the variable $php_errormsg.

Check PHP Error Control for more details.

Actually, I prefer to use expression widthout '@' and handle all exceptions with a function that log all message in a file with error_log(). Something like:

function error_handler($errno, $errstr, $errfile=null, $errline=null, $errcontext=null) {
    error_log($errstr, 3, 'debug.log');
}

set_error_handler('error_handler', ERROR_REPORTING);

I cant figure out the diffrence between following two syntaxes

12 Answers12