Structure vs Class in C++

February 17, 2023

Structure vs Class

On this page we will discuss about difference between structure and class in C++. In C++, a structure is a user-defined data type that groups together variables of different data types, and a class is a more flexible version of a structure.

Both structures and classes allow you to define and create custom data types that can be used to represent real-world objects or concepts in your code.

Here we will discuss the key difference between structure in C and C++ despite syntactical similarities.

Key differences between Structure and Class in C++

	Parameters	Structure	Class
1.	Access level	By default, members of a structure have public access.	By default, members of a class have private access.
2.	Syntax	struct structure_name { data_type member1; data_type member2; … data_type member_n; };	class class_name { access_specifier: data_type member1; data_type member2; … data_type member_n; access_specifier: return_type member_function1(args); return_type member_function2(args); … };
3.	Inheritance	It does not support inheritance.	It supports inheritance.
4.	Polymorphism	It does not support polymorphism.	It supports polymorphism.
5.	Default constructor	It does not have default constructor.	It has default constructor if no other constructors are defined.
6.	Size of object	It is smaller in size compared to classes.	It is generally larger in size compared to structures.
7.	Member functions	It can’t have member functions.	It can have member functions.
8.	Virtual functions	It can’t have virtual functions.	It can have virtual functions.
9.	Semantic difference	It is used to represent a collection of related data.	It is used to represent objects with both data and behaviour.

Note: The differences are mainly due to the default access levels and some additional features classes has like Encapsulation and Polymorphism. You can use both of them as you want, depending on the problem you're solving and the design choices you make.

Function in C++

Static Members in C++

virtual in C++

Pointers in C++

References in C++

Example of Structure

Run

#include <iostream>
using namespace std;

struct Point
{
  int x;
  int y;
};

int main()
{
  Point point1;
  point1.x = 10;
  point1.y = 20;

  cout << "Point: (" << point1.x << ", " << point1.y << ")" << endl;

  return 0;
}

Output:

Point: (10, 20)

Example of Class

Run

#include <iostream>
using namespace std;

class Point
{
private:
  int x_;
  int y_;
public:
    Point(int x, int y):x_ (x), y_ (y)
  {
  }
  void setX(int x)
  {
    x_ = x;
  }
  void setY(int y)
  {
    y_ = y;
  }
  int getX()
  {
    return x_;
  }
  int getY()
  {
    return y_;
  }
};

int main()
{
  Point point1(10, 20);
  cout << "Point: (" << point1.getX() << ", " << point1.getY() << ")" << endl;

  point1.setX(5);
  point1.setY(15);
  cout << "Point: (" << point1.getX() << ", " << point1.getY() << ")" << endl;

  return 0;
}

Output:

Point: (10, 20)
Point: (5, 15)

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Structure vs Class in C++