Why is the internal variable of the function referenced externally, not automatically deleted after execution?

Why is the internal variable of the function referenced externally, not automatically deleted after execution? This post is finally edited by function & nbsp; counter ($ d0) & nbsp ;{& nbsp; & nbsp; & nbsp; $ why is the internal variable of the counter function referenced externally, not automatically deleted after execution?

This post was last edited by baidu_25468825 at 03:01:59 on

Function counter ($ d = 0 ){
$ Counter = 1 + $ d;
Return function () use (& $ counter) {return $ counter ++ ;};
}

$ A = counter ();
Echo $ a (); // 1
Echo $ a (); // 2

Problem:

$ A = counter (); // returns the closed function. after the function is executed, all internal variables are deleted;
Ref = 2? Okay, it is equal to 2; delete one; there is also a reference;
The variables in the function are local, and the memory address can be publicly used ??????????
I cannot understand how the memory address of a local variable can be global;
Echo $ a (); // 1
Echo $ a (); // 2

I don't quite understand it. please answer it in detail. I haven't understood it after two hours of research;


----------

Function aaa (){
$ A = 1;
Return function () use (& $ a) {return $ a ++ ;}; // This $ a inherits the $ a memory address of the parent scope;
}
 
// First, a closed function is returned: function () use (& $ a) {return $ a ++ ;}
// Function nesting function. When an outer function is executed, its internal function becomes a global scope;
// Closed function: it has control over $ a memory, and is also a global function. a bit ......
 
$ A = aaa (); // after aaa () is executed, the variable is cleared. because & reference, ref_count-1 does not release the memory;
Echo $ a (); // 1;
Echo $ a (); // 2;
 

I am not sure whether the analysis is correct. please correct the information;
------ Solution ----------------------
What does it mean?
Since you use (& $ counter), of course you need to know the consequences of doing so, because that &, the rules have changed.

Since it is a reference, it means that two or more variables direct to the same data zone and delete one.
------ Solution ----------------------
JavaScript closures are quite popular, but it seems that few php...
After an anonymous function is assigned to $ a, it is equivalent to the birth of a global function, but this is not the focus...
If $ counter in use is just a copy call, the memory will be released after the value of $ a = $ counter ();
It's just a pointer... so the block exists in this anonymous function and remains
$ Counter in the anonymous function only belongs to $ a. If you make $ B = counter ();, there will be another independent $ counter