PHP中__construct(),类的构造函数详解

function __constrct([参数列表]){
    方法体 //通常用来对成员属性进行初始化赋值
}

<?php
    class Person
    {                                                                      
            public $name;        
            public $age;        
            public $sex;        
                                                                 
        /**
         * 显示声明一个构造方法且带参数
         */                                                                                       
        public function __construct($name="", $sex="男", $age=22)
        {      
            $this->name = $name;
            $this->sex = $sex;
            $this->age = $age;
        }
        
        /**
         * say 方法
         */
        public function say()
        { 
            echo "我叫：" . $this->name . "，性别：" . $this->sex . "，年龄：" . $this->age;
        }   
                                                                                           
    }

$Person1 = new Person();
echo $Person1->say(); //输出:我叫：，性别：男，年龄：27

$Person2 = new Person("小明");
echo $Person2->say(); //输出：我叫：张三，性别：男，年龄：27

$Person3 = new Person("李四","男",25);
echo $Person3->say(); //输出：我叫：李四，性别：男，年龄：25