基类的protected成员可以被派生类成员访问

class A
{
  protected: //改成private会报错: "A::numX" (已声明 所在行数 : 10) 不可访问
     int numX = 100;
};

class B: public A
{
  public:
     void assign(void) { numY = numX; }
     int getY(void) { return numY; }
  private:
     int numY = 0;
};

int main(int argc, char *argv[])
{
  B b;
  printf("numY = %d\n", b.getY());
  b.assign();
  printf("numY = %d\n", b.getY());

  system("pause");
  return 0;
}

 

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