The difference between static methods and objects in php

There are four key differences between static methods and object methods in PHP: 1. Static methods can be called directly through the class name, while object methods need to be called through instances of the class; 2. Static methods have only one instance in memory. 3. Static methods can only access and operate static properties, while object methods can access and operate static properties and non-static properties; 4. Static methods There are no object dependencies, and object methods must be called on instances of the class.

Operating system for this tutorial: Windows 10 system, php8.1.3 version, Dell G3 computer.

In PHP, there are several key differences between static methods and object methods:

1. Calling method: Static methods can be called directly through the class name, while object methods need to be called through Class instance (object) to call.

2. Memory allocation: Static methods have only one copy in memory, while object methods have an independent copy in each instance of the class. This means that when you call a static method, you do not need to create an instance of the class, but when you call an object method, you need to create an instance of the class first.

3. Accessing class properties: Static methods can only access and operate static properties (i.e., class properties), and cannot directly access and operate non-static properties (i.e., object properties). Object methods can access and operate static properties as well as non-static properties.

4. Object dependency: Static methods have no object dependencies and do not need to care about the instantiation process of the class. While an object method must be called on an instance of the class, it can use the class's properties and methods, and may depend on specific object state.

The following is a sample code that demonstrates the definition and use of static methods and object methods:

class MyClass {
    public static $staticProperty = 'Static Property';
    public $objectProperty = 'Object Property';
    public static function staticMethod() {
        echo 'Static Method called.' . PHP_EOL;
        echo self::$staticProperty . PHP_EOL; // 访问静态属性
        // echo $this->objectProperty . PHP_EOL; // 错误：不能访问非静态属性
    }
    public function objectMethod() {
        echo 'Object Method called.' . PHP_EOL;
        echo self::$staticProperty . PHP_EOL;  // 访问静态属性
        echo $this->objectProperty . PHP_EOL; // 访问非静态属性
    }
}
MyClass::staticMethod(); // 调用静态方法，输出：Static Method called. Static Property
$obj = new MyClass();
$obj->objectMethod(); // 调用对象方法，输出：Object Method called. Static Property Object Property

To summarize, static methods can be called directly through the class name, no An object instance is required, and only static properties can be accessed and manipulated; object methods must be called through object instances, and static and non-static properties can be accessed and manipulated. Choosing which method to use depends on specific needs and scenarios.

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