Interview question
Explain inheritance in PHP with an example. PHP में inheritance एक उदाहरण के साथ समझाएं।
Answer
Short Answer
PHP supports 8 primitive data types categorized into scalar, compound, and special types. These include String, Integer, Float, Boolean (Scalar), Array, Object (Compound), and NULL, Resource (Special).
Code Example: Common Data Types
Since PHP is a loosely typed language, you do not need to explicitly declare data types when creating variables. PHP automatically converts the variable to the correct data type based on its value.
// Scalar Types
$name = "Prepiq"; // String
$age = 25; // Integer
$price = 19.99; // Float (Double)
$isActive = true; // Boolean
// Compound Types
$colors = ["Red", "Blue", "Green"]; // Array
$user = new stdClass(); // Object
// Special Types
$connection = null; // NULL
// $file = fopen("test.txt", "r"); // Resource
Important Points
- Loosely Typed: You can change a variable from an integer to a string simply by reassigning it.
- Type Juggling: PHP will automatically attempt to convert types during comparisons (e.g.,
"1" == 1is true). This is why using strict comparison (===) is recommended.
Inheritance एक class (child) को दूसरी class (parent) की properties और methods extends कीवर्ड से reuse करने देता है, कोड duplication से बचाते हुए।
class Animal {
protected string $name;
public function __construct(string $name) { $this->name = $name; }
public function eat(): string { return $this->name . ' is eating'; }
}
class Dog extends Animal {
public function bark(): string { return $this->name . ' says Woof!'; }
}
$dog = new Dog('Rex');
echo $dog->eat(); // Rex is eating (inherited)
echo $dog->bark(); // Rex says Woof! (अपना method)| टर्म | मतलब |
|---|---|
| extends | parent class से inherit करने का कीवर्ड |
| parent:: | parent class का method या constructor call करने के लिए |
| PHP सीमा | सिर्फ single inheritance allowed (एक parent class); ज़्यादा के लिए interfaces/traits इस्तेमाल करें |
इंटरव्यू टिप: बताएं PHP multiple class inheritance सपोर्ट नहीं करता, लेकिन traits यह कमी पूरी करते हैं।
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