解析错误：语法错误，当我在php上使用'class'时意外'''

class MailAuthGen{
    var $mail='test@mail.com';
    var $findUid = "SELECT uid from 'accounts' where email='$mail'";
    function abc() {
        echo $this->findUid;
    }
}

when I load this page, the page shows

Parse error: syntax error, unexpected '"'

Even

$findUid = "SELECT uid from 'accounts' where email='".$mail."'";

didn't work.

But, when I didn't use 'class', it executed well.

What's the problem?

The error is with this line. You can't evaluate any variables when declaring properties.

var $findUid = "SELECT uid from 'accounts' where email='$mail'";
//                              You can't do this ------^

A common workaround is something like:

var $findUid = "SELECT uid from 'accounts' where email='%s'";

Where you can interpolate the value later.