C++中子类调用父类的有参构造函数

 转自：https://blog.csdn.net/sddyljsx/article/details/9156055

参考：

https://blog.csdn.net/qq_36846891/article/details/69666437 //java中子类构造与父类构造

https://blog.csdn.net/dan_lionly/article/details/52314869 //c++中子类构造与父类构造

#include <iostream>
using namespace std;
class A
{
public:
int a;
int b;
A()
{
cout<<"A Constructed\n";
}
};
class B:A
{
public:
int c;
int d;

B()
{
cout<<"B Constructed\n";
}

};

int main()
{

B b;
return 1;

}

如上面代码所示，B类继承自A类，当生成B的实例b时，要先执行A的构造函数，然后执行B的构造函数。结果如下所示:

若B使用有参构造函数，如下面代码所示，仍然会调用A的无参构造函数。

#include <iostream>

using namespace std;

class A
{
public:
int a;
int b;

A()
{
cout<<"A Constructed 1\n";
}
A(int a,int b)
{
this->a=a;
this->b=b;
cout<<"A Constructed 2\n";
}

};

class B:A
{
public:
int c;
int d;

B()
{
cout<<"B Constructed 1\n";
}

B(int c,int d)
{
this->c=c;
this->d=d;
cout<<"B Constructed 2\n";
}

};

int main()
{
B b(1,1);
return 1;
}

运行结果:

但是如何在构造函数中调用父类的有参构造函数呢？实现代码如下：​​​​​​​

#include <iostream>
using namespace std;

class A
{
public:
int a;
int b;
A()

{
cout<<"A Constructed 1\n";
}

A(int a,int b)
{
this->a=a;
this->b=b;
cout<<"A Constructed 2\n";
}

};

class B:A
{

public:
int c;
int d;

B()
{
cout<<"B Constructed 1\n";
}

B(int c,int d):A(100,200)
{
this->c=c;
this->d=d;
cout<<"B Constructed 2\n";
}
};

int main()
{
B b(1,1);
return 1;
}

运行结果：