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Luca Vicini
Courses Plus Student 8,594 PointsScope and lifespan of variables in PHP
I have troubles in understanding the scope of variable in PHP. for example: in start.php I define $a = 123; Then following a link the visitor is transferred to end.php Within end.php will be $a defined with the value 123?
On a different context. I have two concurrent users accessing the same web page. Are the two sessions living in completely separated sandboxes?
Now, let's suppose that I am executing a php scrip (example.php). I close the browser window and reopen example.php immediately. Are the variable from the first session still available in the second session?
2 Answers
Aaron Graham
18,033 Points"... will be $a defined with the value 123?" - short answer no. It actually depends on where you declare $a. If it is a session variable or in a cookie, it actually would be defined in end.php. In general though, a variable doesn't have any scope outside the current execution context. In other words, if you go to start.php, the server runs the script, evaluates variables, expressions, etc., returns the output and then throws everything away. When you go to end.php, that script would be run including anything that was declared in that particular script. The values don't persist between pages. This is why sessions and cookies were developed in the first place.
As for your second question, each request to the server will run in it's own thread, or sandbox, if you like.
Luca Vicini
Courses Plus Student 8,594 PointsThanks Aaron, that answer perfectly my question.
Aaron Graham
18,033 Pointsglad I could help :-)