C++（二十八） — 构造函数的初始化列表

class A
{
public:
    A(int a_)
    {
        a = a_;
        cout << "A的构造函数，a: " << a << endl;
    }
    ~A()
    {
        cout << "A的析构函数 " << endl;
    }
private:
    int a;
};

class B
{
public:
    B(int b1_, int b2_) :a1(1), a2(2)
    {
        b1 = b1_;
        b2 = b2_;
    }
    B(int b1_, int b2_, int m, int n) :a1(m), a2(n)
    {
        b1 = b1_;
        b2 = b2_;
        cout << "B的构造函数" << endl;
    }
    ~B()
    {
        cout << "B的析构函数 " << endl;
    }
private:
    int b1, b2;
    //A类别构造函数的调用与定义顺序有关，与初始化列表顺序无关。
    A a1;
    A a2;
};

void display()
{
    B obj_b1(1, 2, 3, 4);
}

void main()
{
    //A a0(10);
    //B obj_b0(1, 2);
    //B obj_b1(1, 2, 3, 4);
    display();

    system("pause");
}