public、potected 、private继承下的子类对父类成员的访问情况

#include<iostream>
  2 #include<string>
  3 using namespace std;
  4 class parent{
  5 protected:
  6         int m_a;
  7         int m_b;
  8 public:
  9         int m_c;
 10         void set(int a,int b,int c){
 11                 m_a = a;
 12                 m_b = b;
 13                 m_c = c;
 14         }
 15 };
 16 class child_A:public parent{
 17 public:
 18         void print(){
 19                 cout << "m_a=" << m_a << endl;
 20                 cout << "m_b=" << m_b << endl;
 21                 cout << "m_c=" << m_c << endl;
 22         }
 23 };
 24 class child_B:protected parent{
 25 public:
 26         void print(){
 27                 cout << "m_a=" << m_a << endl;
 28                 cout << "m_b=" << m_b << endl;
 29                 cout << "m_c=" << m_c << endl;
                                                                                                                                   1,8          顶端
 30         }
 31 
 32 };
 33 class child_C:private parent{
 34 public:
 35         void print(){
 36                 cout << "m_a=" << m_a << endl;
 37                 cout << "m_b=" << m_b << endl;
 38                 cout << "m_c=" << m_c << endl;
 39         }
 40 
 41 };
 42 int main(){
 43         child_A a;//public继承
 44         child_B b;//protected 继承
 45         child_C c;//private继承
 46         a.m_c = 100;//100
 47         //b.m_c = 100;//100
 48         //c.m_c = 100;
 49         return 0;
 50         a.print();
 51         b.print();
 52         c.print();
 53         cout << endl;
 54         a.set(1,1,1);
 55         b.set(2,2,2);
 56         c.set(3,3,3);
 57 }
//结果

class.cpp:10:7: error: ‘void parent::set(int, int, int)’ is inaccessible
void set(int a,int b,int c){
^
class.cpp:54:13: error: within this context
b.set(2,2,2);
^
class.cpp:54:13: error: ‘parent’ is not an accessible base of ‘child_B’
class.cpp:10:7: error: ‘void parent::set(int, int, int)’ is inaccessible
void set(int a,int b,int c){
^
class.cpp:55:13: error: within this context
c.set(3,3,3);
^
class.cpp:55:13: error: ‘parent’ is not an accessible base of ‘child_C’