Usage of or in PHP statements

We often see this statement: $ file = fopen ($ filename, 'r') ordie ("negative loss, cannot open: $ filename"); or here we know this, because the data types are not differentiated in PHP, $ file can be int or bool. Therefore, such statements do not often see such statements:
$ File = fopen ($ filename, 'r') or die ('negative Referer, cannot open: $ filename ');
Or this is the case here. because the data type is not distinguished in PHP, $ file can be either int or bool, so such a statement will not report an error. However, some friends may not understand the process.
In most languages, in statements such as bool or bool, if the previous value is true, the latter value will not be determined. So if the fopen function is executed accurately, an int value greater than 0 will be returned (this is actually "true"), and the subsequent statements will not be executed. If the fopen function fails to be executed, false is returned, and the following expression is determined to be true.
After the result is executed by die (), no matter what is returned, the program has been executed and the specified error information is displayed, thus achieving the debugging goal.
That's it. :)