1、工厂模式

1、why

#include <iostream>

class Phone {
};

class XiaoMi : public Phone {
};

class Apple : public Phone {
};

class Huawei : public Phone {
};

class Oppo : public Phone {
};

class Vivo : public Phone {
};

int main() {
    XiaoMi* xiaomiPhone = new XiaoMi();
    Apple* applePhone = new Apple();
    Huawei* HuaweiPhone = new Huawei();
    Oppo* oppo = new Oppo();
    Vivo* vivo = new Vivo();
    return 0;
}

2、when

3、what

4、how