Public And Private

Private properties and functions can be accessed or modified only in the class body.

Public members can be accessed or modified anywhere - class body, main function, other function.

It can be understood via the following code:

#include <string> #include <iostream> using namespace std; class Person { private: // set default value for id string id = "1"; public: string name; int age; void printData() { cout << "Name:" << name; cout << endl; // new line cout << "Age: " << age; cout << endl; // new line cout << "Id: " << id; } }; int main() { Person personObject; personObject.name = "John"; personObject.age = 20; // personObject.id = "new_id"; personObject.printData(); }

Output:

Name: John Age: 20 Id: 1

There are a couple of things to notice about the private property id and the public properties name and age:

• Both public and private properties can be accessed/modified in the class body: for public properties - lines 18 and 20, for private properties - line 22.
• Outside the class body (like the main function) only public properties can be accessed/modified - lines 30 and 31.
• If we uncomment line 32 the code will not compile. Because a private member (id in this case) cannot be accessed/modified outside the class body.