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PHP and MySQL

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Call

Calling or using a class in PHP involves creating an instance of the class and then accessing its properties and methods. Here's a detailed guide on how to do this.

Step-by-Step Guide

  1. Define the Class:
    • Define a class with properties and methods.
  2. Create an Instance of the Class:
    • Use the new keyword to create an object (instance) of the class.
  3. Access Properties and Methods:
    • Use the -> operator to access properties and methods of the object.

Example

Let's define a class Car and then create an instance of it and call its methods

<?php
// Step 1: Define the Class
class Car {
   // Properties
   public $make;
   public $model;
   public $year;
   // Constructor
   public function __construct($make, $model, $year) {
       $this->make = $make;
       $this->model = $model;
       $this->year = $year;
   }
   // Methods
   public function display() {
       return "This car is a $this->year $this->make $this->model.";
   }
   public function start() {
       return "The car has started.";
   }
}
// Step 2: Create an Instance of the Class
$myCar = new Car("Toyota", "Corolla", 2021);
// Step 3: Access Properties and Methods
echo $myCar->display(); // Outputs: This car is a 2021 Toyota Corolla.
echo "\n"; // New line for better readability
echo $myCar->start();   // Outputs: The car has started.
?>

Explanation

Define the Class:

  • class Car { ... }: This defines the Car class.
  • Properties: $make, $model, $year to hold the car's make, model, and year.
  • Constructor: __construct($make, $model, $year) to initialize the properties when a new object is created.
  • Methods: display() and start() to provide functionality to the class.

Create an Instance:

  • $myCar = new Car("Toyota", "Corolla", 2021);: This creates a new instance of the Car class, passing the make, model, and year to the constructor.

Access Properties and Methods:

  • echo $myCar->display();: Calls the display method of the $myCar object.
  • echo $myCar->start();: Calls the start method of the $myCar object.

Additional Example

You can also define a class with more properties and methods to demonstrate different functionalities:

<?php
class Person {
   // Properties
   public $firstName;
   public $lastName;
   public $age;
   // Constructor
   public function __construct($firstName, $lastName, $age) {
       $this->firstName = $firstName;
       $this->lastName = $lastName;
       $this->age = $age;
   }
   // Methods
   public function getFullName() {
       return "$this->firstName $this->lastName";
   }
   public function isAdult() {
       return $this->age >= 18 ? "Adult" : "Not an Adult";
   }
}
// Create an instance of the class
$person = new Person("John", "Doe", 25);
// Access the methods
echo $person->getFullName(); // Outputs: John Doe
echo "\n"; // New line for better readability
echo $person->isAdult();     // Outputs: Adult
?>

Summary

  1. Define the Class: Use class ClassName { ... }.
  2. Create an Instance: Use new ClassName(parameters);.
  3. Access Properties and Methods: Use $object->property and $object->method().



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