1.组合类必须采用初始化参数列表写法

2.组合类必须调用分支类的构造函数

1.ear与eye类

class ear {
public:ear(int num,string name):num(num),name(name){cout << "构造ear" << endl;}
private:int num;string name;
};
class eye {
public:eye(int num,string name) :num(num), name(name) {cout << "构造eye" << endl;}
private:int num;string name;
};

组合成head类

class head {
public:head(int earnum, string earname, int eyenum, string eyename, int num, string name) :r(earnum, earname), e(eyenum, eyename) {this->num = num;this->name = name;cout << "构造head" << endl;}
private:int num;string name;ear r;eye e;
};

2.main

int main() {head(10,"ear",20,"eye",30,"head");return 0;
}

结果：