PHP面向对象：解决继承中NULL值输出问题——构造函数与类关系辨析

<?php
class Patient {
    private $name;
    private $age;
    private $gender;

    /**
     * 构造函数，用于初始化Patient对象的属性
     * @param string $name 患者姓名
     * @param int $age 患者年龄
     * @param string $gender 患者性别
     */
    public function __construct($name, $age, $gender) {
        $this->name = $name;
        $this->age = $age;
        $this->gender = $gender;
    }   

    public function getName() {
        return $this->name;
    }

    public function getAge() {
        return $this->age;
    }

    public function getGender() {
        return $this->gender;
    }
}

<?php
// ... Patient class as defined above ...

class Clinic {
    private $patients = []; // 使用数组存储Patient对象

    /**
     * 获取诊所中的所有患者
     * @return array Patient对象数组
     */
    public function getPatients() {
        return $this->patients;
    }

    /**
     * 为诊所分配一个新患者
     * @param string $name 患者姓名
     * @param int $age 患者年龄
     * @param string $gender 患者性别
     */
    public function assignPatient($name, $age, $gender) {
        // 使用Patient类的构造函数创建新患者对象
        $this->patients[] = new Patient($name, $age, $gender);
    }

    /**
     * 根据索引删除患者
     * @param int $index 要删除患者的数组索引
     */
    public function deletePatient($index) {
        if (isset($this->patients[$index])) {
            unset($this->patients[$index]);
            // 可选：重新索引数组，但通常在删除后保持索引不变更常见
            // $this->patients = array_values($this->patients); 
        }
    }
}

<?php
class Patient {
    private $name;
    private $age;
    private $gender;

    public function __construct($name, $age, $gender) {
        $this->name = $name;
        $this->age = $age;
        $this->gender = $gender;
    }   

    public function getName() {
        return $this->name;
    }

    public function getAge() {
        return $this->age;
    }

    public function getGender() {
        return $this->gender;
    }
}

class Clinic {
    private $patients = [];

    public function getPatients() {
        return $this->patients;
    }

    public function assignPatient($name, $age, $gender) {
        $this->patients[] = new Patient($name, $age, $gender);
    }

    public function deletePatient($index) {
        unset($this->patients[$index]);
    }
}

// 实例化Clinic对象
$clinic = new Clinic();

// 分配患者
$clinic->assignPatient("Patrick star", 18, "Male");
$clinic->assignPatient("SpongeBob Squarepants", 17, "Male");
$clinic->assignPatient("Eugene Krab", 28, "Male");

// 删除索引为1的患者 (SpongeBob Squarepants)
$clinic->deletePatient(1);

// 输出当前诊所中的患者列表
print_r($clinic->getPatients());

?>

Array
(
    [0] => Patient Object
        (
            [name:Patient:private] => Patrick star
            [age:Patient:private] => 18
            [gender:Patient:private] => Male
        )

    [2] => Patient Object
        (
            [name:Patient:private] => Eugene Krab
            [age:Patient:private] => 28
            [gender:Patient:private] => Male
        )

)