我应该在我的PHP代码中使用at符号（@）

Question

I have recently learned how to use the @ symbol in my php code and I have learned to love it. However I have also been told that @ is not efficient performance wise. Is the elegance it provides enough to excuse the performance hit it might or might not create.

One common usage which I implement is in an if statement when trying to access an array.

if( $value = @$array['key'] )
// value exists and we can access it

Because it returns null instead of displaying an error it is a useful tool in situations as this one.

Answer 1

Suppressing errors in this way is useful, but not for your example because there are more traditional ways to check for those potential errors.

I use it sometimes, but normally for IO operations. For example.

$sample = 'sample.txt';

if (!file_exists($sample)) {
    throw new FileNotFoundException($sample);
}

if (!$fp = @fopen('sample.txt', 'r')) {
    throw new IOException($sample, error_get_last()['message']);
}

The exceptions in this are classes I would have created. The goal is to open a file for reading, first I need to check the file exists, thats easy, if it doesn't I can throw a relevant error.

Next is to open the file. Well this is a nothing or all operation and there could be a multitude of reasons why it won't work (permissions for example).

I want to handle the the problem if there is one (in this case by catching an exception) so I suppress the error (because I don't want users to see it), but I do want to know what happened, so I catch the exception, log the message somewhere and redirect the user somewhere else.

I use @ because I don't know what the error might be and because depending on the PHP configuration it will always trigger an error regardless of what you do with the return value.

Don't use it for something like getting an array value by index, because there are very few types of problems with this and they can all be checked for before starting the operation.