C++ Tutorial/Class/public inheritance

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Base-Class Access Control

#include <iostream>
using namespace std;
   
class base {
  int i, j;
public:
  void set(int a, int b) { i=a; j=b; }
  void show() { cout << i << " " << j << "\n"; }
};
   
class derived : public base {
  int k;
public:
  derived(int x) { k=x; }
  void showk() { cout << k << "\n"; }
};
   
int main()
{
  derived ob(3);
   
  ob.set(1, 2); // access member of base
  ob.show(); // access member of base
   
  ob.showk(); // uses member of derived class
   
  return 0;
}

Demonstrate public inheritance.

#include <iostream> 
using namespace std; 
 
class BaseClass { 
  int i, j; 
public: 
  void set(int a, int b) { 
     i = a; j = b; 
  } 
  void show() { 
     cout << i << " " << j << "\n"; 
  } 
}; 
 
class DerivedClass : public BaseClass { 
  int k; 
public: 
  DerivedClass(int x) { 
     k = x; 
  } 
  void showDerivedClass() { 
     cout << k << "\n"; 
  } 
 
  // i = 10; // Error! i is private to BaseClass and access is not allowed. 
}; 
 
int main() 
{ 
  DerivedClass ob(3); 
 
  ob.set(1, 2); // access member of base class 
  ob.show();    // access member of base class 
 
  ob.showDerivedClass();   // uses member of derived class 
 
  return 0; 
}
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Inheritance and protected Members

#include <iostream>
using namespace std;
   
class base {
protected:
  int i, j; // private to base, but accessible by derived
public:
  void set(int a, int b) { i=a; j=b; }
  void show() { cout << i << " " << j << "\n"; }
};
   
class derived : public base {
  int k;
public:
  // derived may access base"s i and j
  void setk() { k=i*j; }
   
  void showk() { cout << k << "\n"; }
};
   
int main()
{
  derived ob;
   
  ob.set(2, 3); // OK, known to derived
  ob.show(); // OK, known to derived
   
  ob.setk();
  ob.showk();
   
  return 0;
}

Inherited as public

#include <iostream>
using namespace std;
class base {
protected:
  int i, j;
public:
  void set(int a, int b) { 
     i=a; 
     j=b; 
  }
  void show() { 
     cout << i << " " << j << "\n"; 
  }
};
class derived1 : public base {
  int k;
public:
  void setk() { 
     k = i*j; 
  }
  void showk() { 
     cout << k << "\n"; 
  }
};
class derived2 : public derived1 {
  int m;
public:
  void setm() { 
     m = i-j; 
  }
  void showm() { 
     cout << m << "\n"; 
  }
};
int main()
{
  derived1 ob1;
  derived2 ob2;
  ob1.set(2, 3);
  ob1.show();
  ob1.setk();
  ob1.showk();
  ob2.set(3, 4);
  ob2.show();
  ob2.setk();
  ob2.setm();
  ob2.showk();
  ob2.showm();
  return 0;
}
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Источник — «http://cppe.ru/index.php?title=C%2B%2B_Tutorial/Class/public_inheritance&oldid=2336»