Explore OOP in C++ to write cleaner, modular, and scalable code. Learn classes in C++, data hiding, encapsulation, abstraction, inheritance, and polymorphism in C++.

Become  a C++ Programmer

This module aims to teach us how to write cleaner, more modular, and scalable code in C++ by providing an understanding of OOP in C++. We'll start with the basics of object-oriented programming and build up to advanced concepts such as inheritance, data hiding, and polymorphism. Along the way, we'll explore how each concept applies to C++ and how various C++ features facilitate OOP.

Object-Oriented Programming in C++

Derived constructor! 
Base constructor!

Base constructor! 
Derived constructor!

What will be the output of following piece of code?

```C++
class Base {
 public:
 Base(){ 
 cout << "Base constructor!" << endl; 
 }
};

class Derived: public Base {
 public:
 Derived(){
 cout << "Derived constructor!" << endl; 
 }
};

int main(){
 Derived d;
}


```

What will be the output of following piece of code?
<pre><code class="language-C++">class Base {
 public:
 Base(){ 
 cout &lt;&lt; &quot;Base constructor!&quot; &lt;&lt; endl; 
 }
};

class Derived: public Base {
 public:
 Derived(){
 cout &lt;&lt; &quot;Derived constructor!&quot; &lt;&lt; endl; 
 }
};

int main(){
 Derived d;
}


</code></pre>

Figure out the sequence in which destructors will be called:

```C++

class Base {
 public:
 ~Base() { 
 cout << " Base destructor!" << endl; 
 }
};
 
class Derived: public Base {
 public:
 ~Derived() {
 cout << " Derived destructor!" << endl; 
 }
};
 
int main() {
 Derived d;
}

```

Figure out the sequence in which destructors will be called:
<pre><code class="language-C++">
class Base {
 public:
 ~Base() { 
 cout &lt;&lt; &quot; Base destructor!&quot; &lt;&lt; endl; 
 }
};
 
class Derived: public Base {
 public:
 ~Derived() {
 cout &lt;&lt; &quot; Derived destructor!&quot; &lt;&lt; endl; 
 }
};
 
int main() {
 Derived d;
}

</code></pre>

Grandparent print 
Parent print 
Child print

Child print 
Parent print 
Grandparent print

What is the output of the following code?

```C++
class grandParent{
	public:
 void GPprint() {
 	cout << "Grandparent print" << endl;
 }
};

class Parent: public grandParent {
	public:
 void Pprint() {
 	cout << "Parent print" << endl;
 GPprint();
 }
};

class Child : public Parent {
	public:
 void Cprint() {
 	cout << "Child print" << endl;
 Pprint();
 }
};

int main() {
 Child c;
 c.Cprint();
}
 
```

What is the output of the following code?
<pre><code class="language-C++">class grandParent{
	public:
 void GPprint() {
 	cout &lt;&lt; &quot;Grandparent print&quot; &lt;&lt; endl;
 }
};

class Parent: public grandParent {
	public:
 void Pprint() {
 	cout &lt;&lt; &quot;Parent print&quot; &lt;&lt; endl;
 GPprint();
 }
};

class Child : public Parent {
	public:
 void Cprint() {
 	cout &lt;&lt; &quot;Child print&quot; &lt;&lt; endl;
 Pprint();
 }
};

int main() {
 Child c;
 c.Cprint();
}
 
</code></pre>

What will the following program display?
```C++
#include <iostream>
using namespace std;
class B { 
 public: 
 void disp() { 
 cout << "B";
 }
};
class D : public B {
 public:
 void disp() {
 cout << "D";
 }
};
class DD : public D {
};

int main() {
 DD dd;
 dd.disp();
 return 0;
}
```

What will the following program display?
<pre><code class="language-C++">#include &lt;iostream&gt;
using namespace std;
class B { 
 public: 
 void disp() { 
 cout &lt;&lt; &quot;B&quot;;
 }
};
class D : public B {
 public:
 void disp() {
 cout &lt;&lt; &quot;D&quot;;
 }
};
class DD : public D {
};

int main() {
 DD dd;
 dd.disp();
 return 0;
}
</code></pre>

What will be displayed by the following program when it is run?
```c++
#include <iostream>
using namespace std;
class B { 
 private:
 int count = 0;
 public: 
 void inc() { 
 cout << count++;
 }
};
class D : public B {
 public:
 void inc() {
 cout << count++;
 }
};

int main() {
 D d;
 d.inc();
 return 0;
}
```

What will be displayed by the following program when it is run?
<pre><code class="language-c++">#include &lt;iostream&gt;
using namespace std;
class B { 
 private:
 int count = 0;
 public: 
 void inc() { 
 cout &lt;&lt; count++;
 }
};
class D : public B {
 public:
 void inc() {
 cout &lt;&lt; count++;
 }
};

int main() {
 D d;
 d.inc();
 return 0;
}
</code></pre>

What will be the output of the following program?
```c++
#include <iostream>
using namespace std;
class B { 
 public: 
 void greet(int c) {
 cout << c;
 }
 void greet() { 
 cout << "Hello B";
 }
};
class D : public B {
 public:
 void greet() {
 cout << "Hello D";
 }
};

int main() {
 D d;
 d.greet(3);
 return 0;
}
```

What will be the output of the following program?
<pre><code class="language-c++">#include &lt;iostream&gt;
using namespace std;
class B { 
 public: 
 void greet(int c) {
 cout &lt;&lt; c;
 }
 void greet() { 
 cout &lt;&lt; &quot;Hello B&quot;;
 }
};
class D : public B {
 public:
 void greet() {
 cout &lt;&lt; &quot;Hello D&quot;;
 }
};

int main() {
 D d;
 d.greet(3);
 return 0;
}
</code></pre>

What will be the output of the following program?
```c++
#include<iostream>
using namespace std;
 
class B
{
protected:
 int count;
public:
 B() {count = 0;}
};
 
class D1: public B
{
public:
 int sep;
};
 
 
class D2: public B
{
public:
 int set;
};
 
class DD: public D1, public D2
{
public:
 void show() { cout << count; }
};
 
int main(void)
{
 DD d;
 d.show();
 return 0;
}
```

What will be the output of the following program?
<pre><code class="language-c++">#include&lt;iostream&gt;
using namespace std;
 
class B
{
protected:
 int count;
public:
 B() {count = 0;}
};
 
class D1: public B
{
public:
 int sep;
};
 
 
class D2: public B
{
public:
 int set;
};
 
class DD: public D1, public D2
{
public:
 void show() { cout &lt;&lt; count; }
};
 
int main(void)
{
 DD d;
 d.show();
 return 0;
}
</code></pre>

What will be the output of the following program?
```c++
#include<iostream>
using namespace std;
 
class B
{
 protected:
 int count;
 public:
 B() {count = 0;}
 int getCount() { return count; }
};
 
class D : protected B
{
 public:
 void disp() { cout << getCount(); } 
};
 
 
int main(void)
{
 D d;
 d.disp();
 return 0;
}
```

What will be the output of the following program?
<pre><code class="language-c++">#include&lt;iostream&gt;
using namespace std;
 
class B
{
 protected:
 int count;
 public:
 B() {count = 0;}
 int getCount() { return count; }
};
 
class D : protected B
{
 public:
 void disp() { cout &lt;&lt; getCount(); } 
};
 
 
int main(void)
{
 D d;
 d.disp();
 return 0;
}
</code></pre>

What will be the output of the following program?
```c++
#include<iostream>
using namespace std;
 
class B
{
 private:
 const int ID = 10;
 protected:
 int count;
 public:
 B() {count = 0;}
 int getCount() { return count; }
};
 
class D : protected B
{
 public:
 void disp() { cout << getCount(); } 
 int getID() { return ID; }
};
 
 
int main(void)
{
 D d;
 d.getID();
 return 0;
}
```

What will be the output of the following program?
<pre><code class="language-c++">#include&lt;iostream&gt;
using namespace std;
 
class B
{
 private:
 const int ID = 10;
 protected:
 int count;
 public:
 B() {count = 0;}
 int getCount() { return count; }
};
 
class D : protected B
{
 public:
 void disp() { cout &lt;&lt; getCount(); } 
 int getID() { return ID; }
};
 
 
int main(void)
{
 D d;
 d.getID();
 return 0;
}
</code></pre>

What will be the output of the following program?
```c++
#include<iostream>
using namespace std;
 
class B
{
 private:
 const int ID = 10;
 protected:
 int count;
 public:
 B() {count = 0;}
 int getCount() { return count; }
};
 
class D : private B
{
 public:
 void disp() { cout << getCount(); } 
 int getID() { return ID; }
};
 
 
int main(void)
{
 D d;
 d.getID();
 return 0;
}
```

What will be the output of the following program?
<pre><code class="language-c++">#include&lt;iostream&gt;
using namespace std;
 
class B
{
 private:
 const int ID = 10;
 protected:
 int count;
 public:
 B() {count = 0;}
 int getCount() { return count; }
};
 
class D : private B
{
 public:
 void disp() { cout &lt;&lt; getCount(); } 
 int getID() { return ID; }
};
 
 
int main(void)
{
 D d;
 d.getID();
 return 0;
}
</code></pre>

Let's check your understanding of the Inheritance.

Introduction

Classes

Data Hiding

Inheritance

Polymorphism

Conclusion

Quiz