__construct and __destruct in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP code with __construct and __destruct?

Consider the following PHP class with constructor and destructor methods. What will be printed when the script runs?

PHP

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

A

Start
Middle
End

B

Start
End
Middle

C

Middle
Start
End

D

End
Start
Middle

💡 Hint

Remember that the constructor runs when the object is created, and the destructor runs when the script ends or the object is destroyed.

The constructor prints "Start" immediately when the object is created. Then "Middle" is printed. Finally, when the script ends, the destructor prints "End".

❓ Predict Output

intermediate

What happens if __destruct modifies a property before script ends?

Look at this PHP code. What will be the output?

PHP

<?php
class Counter {
    public $count = 0;
    public function __construct() {
        $this->count = 1;
        echo "Construct: {$this->count}\n";
    }
    public function __destruct() {
        $this->count++;
        echo "Destruct: {$this->count}\n";
    }
}
$obj = new Counter();
echo "Count: {$obj->count}\n";
?>

A

Construct: 1
Count: 1
Destruct: 2

B

Construct: 1
Destruct: 2
Count: 1

C

Count: 0
Construct: 1
Destruct: 2

D

Construct: 1
Count: 2
Destruct: 3

💡 Hint

The destructor runs after the last output, so the property change is visible only inside the destructor.

The constructor sets count to 1 and prints it. Then the script prints count (1). Finally, the destructor increments count to 2 and prints it.

🔧 Debug

advanced

What error does this PHP code cause?

Examine this PHP class. What error will occur when running this code?

PHP

<?php
class Sample {
    public function __construct() {
        echo "Hello\n";
    }
}
$obj = new Sample();
?>

A No error, outputs: Hello

B Fatal error: Uncaught Error: Call to undefined method

C Parse error: syntax error, unexpected '}'

D Parse error: syntax error, unexpected end of file

💡 Hint

Check the syntax carefully, especially punctuation after statements.

The echo statement is missing a semicolon at the end, causing a syntax error at the closing brace.

🧠 Conceptual

advanced

When is __destruct called in PHP?

Choose the correct statement about when the __destruct method is called in PHP.

A __destruct is called immediately after the constructor finishes.

B __destruct is called when the object is no longer referenced or script ends.

C __destruct is called before the constructor runs.

D __destruct is called only when the object is explicitly destroyed using unset().

💡 Hint

Think about object lifecycle and script execution.

The destructor runs when the object is no longer used or when the script finishes, not immediately after construction or only on unset.

🚀 Application

expert

How many times is __destruct called in this PHP script?

Analyze this PHP code. How many times will the __destruct method be called before the script ends?

PHP

<?php
class Logger {
    public function __construct() {
        echo "Logger started\n";
    }
    public function __destruct() {
        echo "Logger ended\n";
    }
}
function createLogger() {
    $log = new Logger();
}
createLogger();
$log = new Logger();
?>

A 3

B 1

C 0

D 2

💡 Hint

Consider when objects go out of scope and when destructors run.

The first Logger object inside createLogger() is destroyed when the function ends, calling __destruct once. The second Logger object is destroyed at script end, calling __destruct again. Total 2 times.