Cplusplus Access Specifiers

Access specifiers in C++ play a crucial role in object-oriented programming. 

They control the accessibility of class members, including variables and functions. 

Knowing how to use them effectively can make your code more secure and maintainable. But which ones should you use, and when? Let's dive in.

What Are Access Specifiers?

Access specifiers are keywords you use to define the access level of class members. They determine how these members can be accessed from other parts of your program. C++ provides three primary access specifiers: public, private, and protected.

The Role of Access Specifiers in C++

Access specifiers act like traffic signals for your code. They regulate which parts of your program can interact with certain components of a class. For anyone dealing with C++ classes, understanding these specifiers is as essential as a compass to a navigator.

Exploring Public Access Specifier

When you declare a class member as public, it's like putting up a welcome sign. It means any part of your program can access this member. It’s open to all, but it might not always be the safest choice.

Example:

#include <iostream>
using namespace std;

class Car {
public:
    string brand;
    void showBrand() {
        cout << "Car brand: " << brand << endl;
    }
};

int main() {
    Car myCar;
    myCar.brand = "Toyota";
    myCar.showBrand();
    return 0;
}

In this example, brand and showBrand() are public. You can access them directly outside the Car class.

The Secure Private Specifier

Think of the private specifier as a locked box. Only the class that owns it has the key. This means private members can only be accessed by functions that belong to the same class.

Example:

#include <iostream>
using namespace std;

class BankAccount {
private:
    double balance;
public:
    void setBalance(double b) {
        balance = b;
    }
    double getBalance() {
        return balance;
    }
};

int main() {
    BankAccount account;
    account.setBalance(150.50);
    cout << "Account balance: $" << account.getBalance() << endl;
    return 0;
}

Here, balance is private, ensuring that only the BankAccount class can modify it directly.

The Flexible Protected Access Specifier

Protected is like a club with exclusive membership. Members of the class and its derived classes can access protected members. It strikes a balance between public and private.

Example:

#include <iostream>
using namespace std;

class Animal {
protected:
    string name;
public:
    void setName(string n) {
        name = n;
    }
};

class Dog : public Animal {
public:
    void showName() {
        cout << "Dog's name: " << name << endl;
    }
};

int main() {
    Dog myDog;
    myDog.setName("Rex");
    myDog.showName();
    return 0;
}

In the above case, name is protected, making it accessible to Dog, which inherits from Animal.

When to Use Which?

Deciding which access specifier to use can feel like choosing a tool from a kit. Public members offer ease of access but lower security. Private members provide security, making them suitable for sensitive data. Protected should be used when you want derived classes to have special access.

Default Access in Classes

If you don’t specify any access level, C++ defaults to private in a class. This default behavior helps prevent accidental external access to members.

Example:

#include <iostream>
using namespace std;

class SecretBox {
    int secretCode; // Default is private
public:
    void setCode(int code) {
        secretCode = code;
    }
    int getCode() {
        return secretCode;
    }
};

int main() {
    SecretBox box;
    box.setCode(1234);
    cout << "Secret code: " << box.getCode() << endl;
    return 0;
}

In this situation, secretCode is private by default.

Common Mistakes and How to Avoid Them

One common mistake is overusing public access, which can lead to unintentional interference from other parts of your program. Always consider whether a member truly needs to be public.