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Classes & Objects

Class Members

A class is comprised of class members:

  • Attributes, also known as member data, consist of information about an instance of the class.
  • Methods, also known as member functions, are functions that can be used with an instance of the class.
class City {


  // Attribute
  int population;


public:
  // Method
  void add_resident() {
    population++;
  }


};

Constructor

For a C++ class, a constructor is a special kind of method that enables control regarding how the objects of a class should be created. Different class constructors can be specified for the same class, but each constructor signature must be unique.

#include "city.hpp"


class City {


  std::string name;
  int population;


public:
  City(std::string new_name, int new_pop);


};

Objects

In C++, an object is an instance of a class that encapsulates data and functionality pertaining to that data.

City nyc;

Class

A C++ class is a user-defined data type that encapsulates information and behavior about an object. It serves as a blueprint for future inherited classes.

class Person {


};

Access Control Operators

C++ classes have access control operators that designate the scope of class members:

  • public
  • private

public members are accessible everywhere; private members can only be accessed from within the same instance of the class or from friends classes.

class City {


  int population; 


public:
  void add_resident() { 
    population++;
  }


private:
  bool is_capital;


};

Destructor

For a C++ class, a destructor is a special method that handles object destruction, generally focused on preventing memory leaks. Class destructors don’t take arguments as input and their names are always preceded by a tilde ~.

City::~City() {


  // Any final cleanup


}
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