引用的方式覆盖

#include "iostream"
using namespace std;
class base
{
public:
    base() {}
    base(int a, int b) : a(a), b(b)
    {
    }
    int a;
    int b;
};
class step1 : public ::base
{
public:
    step1() {}
};

int main()
{
    step1 rlxy;
    rlxy.a = 100;
    rlxy.b = 200;
    cout << rlxy.a << endl;
    cout << rlxy.b << endl;

    base &ccc = rlxy;
    cout << ccc.a << endl;
    cout << ccc.b << endl;
}

赋值的方式覆盖

#include "iostream"

using namespace std;

class base
{
public:
    base() {}
    base(int a, int b) : a(a), b(b)
    {
    }
    int a;
    int b;
};

class step1 : public ::base
{
public:
    step1() {}
};

int main()
{
    step1 rlxy;
    rlxy.a = 100;
    rlxy.b = 200;
    cout << rlxy.a << endl;
    cout << rlxy.b << endl;

    base ccc = rlxy;
    cout << ccc.a << endl;
    cout << ccc.b << endl;


}