C++ 虚基类构造函数的执行顺序

（1）调用基类的构造函数，多个基类则按派生类声明时

列出的次序、从左到右调用，而不是初始化列表中

的次序。

（2）调用对象成员（子对象）的构造函数，按类声明中

对象成员出现的次序调用，而不是初始化列表中的

次序。

（3）执行派生类的构造函数。

同一层中对虚基类构造函数的调用总是先于普通基类的构

造函数。

#include<iostream>
using namespace std;

class A//基类A
{
public:
A(){cout<<"class A"<<endl;}
};

class B: public A //由A类派生出类B
{
public:
B(){cout<<"class B"<<endl;}
};

class C1:virtual public B //由类B虚拟派生出类C1
{
public:
C1(){cout<<"class C1"<<endl;}
};

class C2:virtual public B //由类B虚拟派生出类C2
{
public:
C2(){cout<<"class C2"<<endl;}
};

class D:public C1, public C2 //由C1和C2派生出类D
{
public:
D(){cout<<"class D"<<endl;}
};

int main()
{
D d;
return 0;
}

#include<iostream>
using namespace std;

class M
{
public:
M(const char *s){cout<<"M:"<<s<<endl;}
};

class A
{
M m;
public:
A(const char* s):m("in A"){cout<<"A:"<<s<<endl;}
};

class B
{
M m;
public:
B(const char* s):m("in B"){cout<<"B:"<<s<<endl;}
};

class C
{
M m;
public:
C(const char* s):m("in C"){cout<<"C:"<<s<<endl;}
};

class D
{
M m;
public:
D(const char* s):m("in D"){cout<<"D:"<<s<<endl;}
};

class E:public A, virtual public B, virtual public C
{
M m;
public:
E(const char* s):A("from E"),B("from E"),C("from E"),m("in E")
{cout<<"E:"<<s<<endl;}
};

class F:virtual public B, virtual public C, public D
{
M m;
public:
F(const char* s):B("from F"),C("from F"),D("from F"),m("in F")
{cout<<"F:"<<s<<endl;}
};

class G:public E, public F
{
M m;
public:
G(const char* s):B("from G"),C("from G"),E("from G"),F("from G"),m("in G")
{cout<<"G:"<<s<<endl;}
};

int main()
{
G g("from main");
return 0;
}