C++中多重继承的构造函数

构造函数是与类同名的类成员函数。构造函数的主要工作是为类对象分配内存。创建对象时会自动调用构造函数。

多重继承：

多重继承是 C++ 的一个特性，其中一个类可以派生自多个（两个或更多）基类。继承类的构造函数按照它们被继承的顺序被调用。

多重继承模型

多重继承的语法：

多重继承的语法：

class S: public A1, virtual A2
{
….
};                                                                                            

Here,
A2(): virtual base constructor
A1(): base constructor
S(): derived constructor

示例 1 ：下面是展示多重继承中构造函数概念的 C++ 程序。

C++

// C++ program to implement
// constructor in multiple 
// inheritance
#include
using namespace std;
class A1
{
  public:
  A1()
  {
    cout << "Constructor of the base class A1 \n";
  }
  
};
  
class A2
{
  public:
  A2()
  {
    cout << "Constructor of the base class A2 \n";
  }
  
};
  
class S: public A1, virtual A2
{
  public:
  S(): A1(), A2()
  {
    cout << "Constructor of the derived class S \n";
  }
};
  
// Driver code
int main()
{
  S obj;
  return 0;
}

输出

Constructor of the base class A2 
Constructor of the base class A1 
Constructor of the derived class S 

示例 2 ：下面是展示多重继承中构造函数概念的 C++ 程序。

C++

// C++ program to implement
// constructors in multiple
// inheritance
#include
using namespace std;
class A1
{
    public:
        A1()
        {
            int a = 20, b = 35, c;
            c = a + b;
            cout << "Sum is:" << 
                     c << endl;
        }
};
  
class A2
{
    public:
        A2()
        {
            int x = 50, y = 42, z;
            z = x - y;
            cout << "Difference is:" << 
                     z << endl;
        }
};
  
class S: public A1,virtual A2
{
    public:
        S(): A1(), A2()
        {
            int r = 40, s = 8, t;
            t = r * s;
            cout << "Product is:" << 
                     t << endl;
        }
};
  
// Driver code
int main()
{
    S obj;
    return 0;
}

输出

Difference is:8
Sum is:55
Product is:320