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This article introduces the knowledge of "how to understand the garbage collection mechanism of destructor and php". In the actual case operation process, many people will encounter such difficulties. Next, let Xiaobian lead you to learn how to deal with these situations! I hope you can read carefully and learn something!

Destructor: Executed when an object becomes garbage or when the object is explicitly destroyed.

GC(Garbage Collector)

In PHP, when no variables point to this object, the object becomes garbage. PHP destroys it in memory.

This is PHP's GC(Garbage Collector) garbage handling mechanism to prevent memory overflow.

When a PHP thread ends, all memory currently occupied is destroyed, as are all objects in the current program.

__destruct() destructor

The__destruct() destructor is executed when garbage objects are collected.

Destructors can also be called explicitly, but don't do it.

Destructors are called automatically by the system. Do not call a fictitious function of an object in your program.

A destructor cannot have parameters.

As shown in the following procedure, all objects are destroyed before the procedure ends. The destructor was called.

The copy code is as follows:

Program Run Results:

0

1

2

3

4

The destructor is now executed

This is generally used to set up, close the database, close the file and other finishing work

When an object does not point, the object is destroyed.

The copy code is as follows:

Program Run Results:

The destructor is now executed

0

1

2

3

4

In line 10 of the above example, we set $p to null or assign $p a string in line 11, so that the object pointed to before $p becomes a garbage object. PHP destroys this object garbage.

php unset variable

The copy code is as follows:

Program Run Results:

Now that $p is destroyed, is the object destroyed?

0

1

2

3

4

Now, if you destroy $p1, there's no more variables pointing to objects.

The destructor is now executed

Unset destroys variables pointing to objects, not the object.

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