__toString for string representation in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of __toString method in PHP class

What is the output of this PHP code when executed?

PHP

<?php
class Fruit {
    private string $name;
    public function __construct(string $name) {
        $this->name = $name;
    }
    public function __toString(): string {
        return "Fruit: " . $this->name;
    }
}
$apple = new Fruit("Apple");
echo $apple;
?>

A Object of class Fruit could not be converted to string

B Fruit: Apple

C Apple

D Fatal error: Cannot access private property Fruit::$name

💡 Hint

The __toString method defines how the object converts to a string.

The __toString method returns 'Fruit: ' concatenated with the private property name. When echoing the object, PHP calls __toString automatically.

❓ Predict Output

intermediate

Behavior of __toString with concatenation

What will be the output of this PHP code?

PHP

<?php
class Person {
    private string $firstName;
    private string $lastName;
    public function __construct(string $first, string $last) {
        $this->firstName = $first;
        $this->lastName = $last;
    }
    public function __toString(): string {
        return $this->firstName . ' ' . $this->lastName;
    }
}
$p = new Person("John", "Doe");
echo "Hello, " . $p . "!";
?>

A Hello, John!

B Hello, Person Object!

C Fatal error: Object of class Person could not be converted to string

D Hello, John Doe!

💡 Hint

Concatenation with a string triggers __toString method.

When concatenating an object with a string, PHP calls __toString to get the string representation. Here it returns first and last name separated by space.

🔧 Debug

advanced

Identify the error in __toString implementation

What error will this PHP code produce when executed?

PHP

<?php
class Book {
    private string $title;
    public function __construct(string $title) {
        $this->title = $title;
    }
    public function __toString() {
        return $this->title;
    }
}
$book = new Book("1984");
echo $book;
?>

A No error, outputs: 1984

B Fatal error: Method Book::__toString() must return a string value

C Warning: __toString method missing return statement

D Parse error: syntax error in __toString method

💡 Hint

Check the return type declaration in __toString method.

The __toString method returns a string and does not declare a return type. This is allowed in PHP. So no error occurs and output is the title.

📝 Syntax

advanced

Which __toString method causes a syntax error?

Which option below contains a syntax error in the __toString method?

A public function __toString(): string { echo "Hello"; }

B public function __toString() { return "Hello"; }

C public function __toString(): string { return "Hello"; }

D } ;"olleH" nruter { gnirts :)(gnirtSot__ noitcnuf cilbup

💡 Hint

The __toString method must return a string, not echo it.

Option A uses echo inside __toString but does not return a string. This causes a fatal error because __toString must return a string.

🚀 Application

expert

Count characters using __toString in a class

Given this PHP class, what is the value of $length after execution?

PHP

<?php
class Message {
    private string $text;
    public function __construct(string $text) {
        $this->text = $text;
    }
    public function __toString(): string {
        return strtoupper($this->text);
    }
}
$msg = new Message("hello world");
$length = strlen((string)$msg);
?>

A Fatal error: Object cannot be converted to string

B 10

C 11

D 0

💡 Hint

strlen counts characters in the string returned by __toString.

The __toString method returns the uppercase version of 'hello world' which is 'HELLO WORLD' with length 11 including the space.