• Skip to primary navigation
  • Skip to content
  • Skip to primary sidebar
  • Skip to secondary sidebar

GoHired

Interview Questions asked in Google, Microsoft, Amazon

Join WeekEnd Online Batch from 4-April-2020 on How to Crack Coding Interview in Just 10 Weeks : Fees just 20,000 INR

  • Home
  • Best Java Books
  • Algorithm
  • Internship
  • Certificates
  • About Us
  • Contact Us
  • Privacy Policy
  • Array
  • Stack
  • Queue
  • LinkedList
  • DP
  • Strings
  • Tree
  • Mathametical
  • Puzzles
  • Graph

Interfaces in C++ (Abstract Classes in C++)

November 5, 2014 by Dhaval Dave

Capabilities of a C++ class without committing to a particular implementation of that class.
The C++ interfaces are implemented using abstract classes

A class is made abstract by declaring at least one of its functions as pure virtual function. A pure virtual function is specified by placing “= 0” in its declaration as follows:

class Shape 
{
public:
// pure virtual function providing interface framework.
virtual int getArea() = 0;
void setWidth(int w)
{
width = w;
}
void setHeight(int h)
{
height = h;
}
protected:
int width;
int height;
};

The purpose of an abstract class is to provide an appropriate base class from which other classes can inherit. Abstract classes cannot be used to instantiate objects and serves only as an interface. Attempting to instantiate an object of an abstract class causes a compilation error.

Thus, if a subclass of an ABC needs to be instantiated, it has to implement each of the virtual functions, which means that it supports the interface declared by the ABC. Failure to override a pure virtual function in a derived class, then attempting to instantiate objects of that class, is a compilation error.

Classes that can be used to instantiate objects are called concrete classes.

// Derived classes
class Rectangle: public Shape
{
public:
int getArea()
{
return (width * height);
}
};
class Triangle: public Shape
{
public:
int getArea()
{
return (width * height)/2;
}
};

int main(void)
{
Rectangle Rect;
Triangle Tri;

Rect.setWidth(5);
Rect.setHeight(7);
// Print the area of the object.
cout
<< "Total Rectangle area: " << Rect.getArea() << endl;

Tri.setWidth(5);
Tri.setHeight(7);
// Print the area of the object.
cout
<< "Total Triangle area: " << Tri.getArea() << endl;

return 0;
}

When the above code is compiled and executed, it produces the following result:

Total Rectangle area: 35
Total Triangle area: 17

Similar Articles

Filed Under: problem Tagged With: c

Reader Interactions

Primary Sidebar

Join WeekEnd Online/Offline Batch from 4-April-2020 on How to Crack Coding Interview in Just 10 Weeks : Fees just 20,000 INR

Join WeekEnd Online/Offline Batch from 4-April-2020

WhatsApp us

Secondary Sidebar

Custom Search

  • How I cracked AMAZON
  • LeetCode
  • Adobe
  • Amazon
  • Facebook
  • Microsoft
  • Hacker Earth
  • CSE Interview

Top Rated Questions

Puzzle : 100 doors in a row Visit and Toggle the door. What state the door will be after nth pass ?

SAP Interview Questions

Find Pythagorean Triplets in an array in O(N)

Handle duplicates in Binary Search Tree

Get K Max and Delete K Max in stream of incoming integers

Trie Dictionary

Printing each word reverse in string

Leetcode: Merge Intervals

Find the element that appears once others appears thrice

Doubly linked list

Test Cases for Round Function

Reliance Jio Software Developer Interview Experience

Find and print longest consecutive number sequence in a given sequence in O(n)

Inorder and Preorder traversals of a Binary Tree given. Output the Postorder traversal of it.

Implement a generic binary search algorithm for Integer Double String etc

Edit Distance ( Dynamic Programming )

Find two non repeating elements in an array of repeating elements

Find Nearest Minimum number in left side in O(n)

Code Chef PRGIFT Solution

Templates in C++

Binary Tree in Java

VMWare Openings

Find the kth number with prime factors 3, 5 and 7

Sort an array according to the order defined by another array

CodeChef’ RRCOPY

Maximum of all subarrays of size k

building with N steps, we can take 1,2,3 steps calculate number of ways to reach at top of building

Closed Parentheses checker

Serialise Deserialise N-ary Tree

Convert number to words java

Copyright © 2025 · Genesis Framework · WordPress · Log in