C++ 基类,子对象,派生类构造函数调用顺序

Posted 2021-08-07 Wecccccccc

#include <iostream>
using namespace std;

class A {
	public:
		A( )  {
			cout << "A Constructor………" << endl;
		}
		~A( )  {
			cout << "A Destructor………" << endl;
		}
};

class B: public A {
	public:
		B( )  {
			cout << "B Constructor………" << endl;
		}
		~B( )  {
			cout << "B Destructor………" << endl;
		}
};

int  main() {
	B   b;
	return 0;
}

#include <iostream>
using namespace std;

class A {
	public:
		A( )  {
			cout << "A Constructor………" << endl;
		}
		~A( )  {
			cout << "A Destructor………" << endl;
		}
};

class B {
	public:
		B( )  {
			cout << "B Constructor………" << endl;
		}
		~B( )  {
			cout << "B Destructor………" << endl;
		}
};

class C: public A, B { //构造函数调用顺序，先A后B，和书写(继承)顺序相同
	public:
		C( )  {
			cout << "C Constructor………" << endl;
		}
		~C( )  {
			cout << "C Destructor………" << endl;
		}
};

int main() {
	C   c;
	return 0;
}

#include <iostream>
using namespace std;

class B1 {
	public:
		B1() {
			cout << "constructing B1 " << endl;
		}
};

class B2 {
	public:
		B2() {
			cout << "constructing B2 " << endl;
		}
};

class B3 {
	public:
		B3() {
			cout << "constructing B3 " << endl;
		}
};

class C {
	public:
		C(): memberB1(), memberB2(), memberB3() {     }
	private://构造函数的调用顺序和对象的创建先后顺序有关
		B2 memberB2;
		B1 memberB1;
		B3 memberB3;
};

int  main() {
	C obj;          //  B2  B1  B3
	return 0;
}

#include <iostream>
using namespace std;

class A {
	public:
		A()  {
			cout << "A Constructor………" << endl;
		}
		~A()  {
			cout << "A Destructor………" << endl;
		}
};

class B {
	public:
		B()  {
			cout << "B Constructor………" << endl;
		}
		~B()  {
			cout << "B Destructor………" << endl;
		}
};

class C: public A {
	private:
		B obj_b;
	public:
		C()  {
			cout << "C Constructor………" << endl;
		}
		~C()  {
			cout << "C Destructor………" << endl;
		}
};

int  main() {
	C   obj;
	return 0;
}