C++ Encapsulation

C++ Encapsulation

The meaning of Encapsulation is to make sure that "sensitive" data is hidden from users.

It is one of the core principles of Object-Oriented Programming. To achieve encapsulation, you must:

1. Declare class variables/attributes as private (so they cannot be accessed directly from outside).
2. Provide public get and set methods to view and modify the values of the private variables safely.

1. Accessing Private Members

Since private variables cannot be accessed directly, we use public methods (commonly referred to as "getters" and "setters") to interact with them.

#include <iostream>
using namespace std;

class Employee {
  private:
    // Private attribute
    int salary;
  public:
    // Setter method
    void setSalary(int s) {
      // We can add logic here! (e.g., ensure salary is not negative)
      if (s > 0) {
        salary = s;
      }
    }
    // Getter method
    int getSalary() {
      return salary;
    }
};
int main() {
  Employee emp;
  // emp.salary = 50000; // This would cause an error!
  emp.setSalary(50000); // Use setter to set the salary
  cout << "Employee Salary: $" << emp.getSalary() << "\n"; // Use getter
  return 0;
}

2. Why Encapsulation?

You might wonder, why write extra code for getters and setters instead of just making variables public?

Here are the main benefits of Encapsulation:

• Control over data: You can control the data going in. For example, in the setSalary method above, we can check if (s > 0) to ensure no one sets a negative salary.
• Read-Only or Write-Only: You can make a variable read-only (by only providing a getter) or write-only (by only providing a setter).
• Flexibility: You can change one part of the code without affecting other parts. You can change how data is stored internally without breaking the code of users who call the getter/setter methods.
• Security: Hiding data reduces the risk of unintended interference or bugs caused by other parts of the program changing data directly.