php 静态方法

class MathUtils {
    // 静态属性
    public static $pi = 3.14159;

    // 静态方法
    public static function calculateCircleArea($radius) {
        return self::$pi * $radius * $radius;
    }
}

// 调用静态方法
$area = MathUtils::calculateCircleArea(5);
echo "圆的面积是: " . $area; // 输出: 圆的面积是: 78.53975

class Example {
    public $nonStaticProperty;

    public static function accessNonStaticProperty() {
        // 创建实例
        $instance = new self();
        $instance->nonStaticProperty = "Hello, World!";
        echo $instance->nonStaticProperty;
    }
}

Example::accessNonStaticProperty(); // 输出: Hello, World!

class Example {
    public static $staticProperty = "Static Property";

    public static function displayStaticProperty() {
        echo self::$staticProperty; // 正确
        // echo $this->staticProperty; // 错误
    }
}

Example::displayStaticProperty(); // 输出: Static Property