How is the exclamation point of php used? Just a piece of code. let me explain it to the younger brother.

How is the exclamation point of php used? Just a piece of code. let me explain it! $ This-& gt; alias & nbsp; & amp; & nbsp; $ this-& gt; alias & nbsp ;=& nbsp; $ this-& gt; table; where the variable type is & nbsp; & nbs php exclamation point? Just a piece of code. let me explain it to you.

! $ This-> alias & $ this-> alias = $ this-> table;

Where the variable type is

/* Alias */
Var $ alias = '';
/* Database table mapped */
Var $ table = '';

The arithmetic priority of this code is unknown. the exclamation point is not ,! $ This-> alias is a Boolean value, $ this-> alias = $ this-> table; it is also a Boolean value, and two Boolean values are used for & operation, there is no place to store the results. what should I do? Is it wrong for me to understand? Share To: alias? &&? $ This-> alias? =? $ This-> table; where the variable type is ???? /*? Alias? */???? Var? $ Alias? =? '';?? /... 'Data-pics = ''>
------ Solution --------------------
Equivalent
If (! $ This-> alias ){
$ This-> alias = $ this-> table;
}