Destructor method in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP destructor example?

Consider the following PHP code. What will it output when run?

PHP

<?php
class Test {
    public function __construct() {
        echo "Constructed\n";
    }
    public function __destruct() {
        echo "Destructed\n";
    }
}
$obj = new Test();
echo "End of script\n";
?>

A

Constructed
Destructed
End of script

B

Constructed
End of script
Destructed

C

Destructed
Constructed
End of script

D

End of script
Constructed
Destructed

💡 Hint

Remember that the destructor runs when the object is destroyed, usually at the end of the script.

The constructor runs first, printing "Constructed". Then the script prints "End of script". Finally, when the script ends and the object is destroyed, the destructor prints "Destructed".

❓ Predict Output

intermediate

What happens when an object is unset explicitly?

What will this PHP code output?

PHP

<?php
class Sample {
    public function __destruct() {
        echo "Bye!\n";
    }
}
$obj = new Sample();
unset($obj);
echo "After unset\n";
?>

A

Bye!

B

After unset
Bye!

C

Bye!
After unset

D

After unset

💡 Hint

Think about when the destructor is called if you unset the object manually.

When you unset the object, the destructor runs immediately, printing "Bye!". Then the script prints "After unset".

🔧 Debug

advanced

Why does this destructor not run as expected?

Look at this PHP code. The destructor message is never printed. Why?

PHP

<?php
class Demo {
    public function __destruct() {
        echo "Destroying\n";
    }
}
function create() {
    $obj = new Demo();
}
create();
echo "Done\n";
?>

A The destructor is not called because PHP requires explicit unset to run destructor.

B The destructor is never called because the object is inside a function and goes out of scope silently.

C The destructor is called but output is buffered and not shown.

D The object is destroyed immediately after create() ends, so destructor runs before echo "Done".

💡 Hint

Think about when local variables inside functions are destroyed.

The object $obj is destroyed as soon as the function create() finishes, so the destructor runs before the "Done" message is printed.

📝 Syntax

advanced

Which option shows the correct destructor syntax in PHP?

Choose the correct way to declare a destructor method in a PHP class.

A public function __destruct() {}

B public function destruct() {}

C function __destruct {}

D public function ~destruct() {}

💡 Hint

Destructor method name must be exactly __destruct with parentheses.

In PHP, the destructor method must be named __destruct with parentheses and a function body.

🚀 Application

expert

What is the output when multiple objects with destructors are created and unset?

Consider this PHP code. What will be the exact output?

PHP

<?php
class A {
    public function __destruct() {
        echo "A destroyed\n";
    }
}
class B {
    public function __destruct() {
        echo "B destroyed\n";
    }
}
$a = new A();
$b = new B();
unset($a);
echo "Middle\n";
?>

A

A destroyed
Middle
B destroyed

B

Middle
A destroyed
B destroyed

C

A destroyed
B destroyed
Middle

D

B destroyed
A destroyed
Middle

💡 Hint

Think about when each object is destroyed and when the script ends.

When unset($a) runs, A's destructor prints "A destroyed". Then "Middle" is printed. At script end, B's destructor runs, printing "B destroyed".