Public Access Specifier in C++

 

In C++, access specifiers control the visibility and accessibility of class members (variables and functions). The public access specifier allows class members to be accessed from outside the class.

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1️⃣ Syntax of public Access Specifier

class ClassName {
public:
    // Public members (accessible from anywhere)
    int data;
    void display() {
        cout << "Data: " << data << endl;
    }
};

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2️⃣ Example: Public Members in a Class

#include <iostream>
using namespace std;

class Car {
public:
    string brand;
    int year;

    void showInfo() {
        cout << "Brand: " << brand << ", Year: " << year << endl;
    }
};

int main() {
    Car car1;
    car1.brand = "Toyota";  // Public member accessible
    car1.year = 2022;
    car1.showInfo();  // Public function called

    return 0;
}

Output:

Brand: Toyota, Year: 2022

Explanation:

• brand and year are declared as public, so they can be accessed directly from main().
• The function showInfo() is also public, so it can be called outside the class.

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3️⃣ Key Characteristics of public Access Specifier

Feature	Description
Visibility	Public members can be accessed from anywhere.
Direct Access	Variables and functions can be accessed directly.
Inheritance Effect	When inherited, public members remain public in the derived class (unless changed).

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4️⃣ Public Access in Inheritance

When a class is inherited using public mode, the public members remain public in the child class.

Example: Public Inheritance

#include <iostream>
using namespace std;

class Parent {
public:
    void showMessage() {
        cout << "This is a public function from Parent class." << endl;
    }
};

class Child : public Parent {  // Public Inheritance
};

int main() {
    Child obj;
    obj.showMessage();  // Accessible because it's public

    return 0;
}

Output:

This is a public function from Parent class.

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5️⃣ When to Use public Access Specifier?

✅ When you need direct access to class members.
✅ When defining interface functions that should be accessible to users.
✅ When implementing class inheritance where functions should remain accessible in derived classes.

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6️⃣ Comparison of Access Specifiers

Access Specifier	Accessible Inside Class	Accessible Outside Class	Accessible in Derived Class
public	✅ Yes	✅ Yes	✅ Yes
private	✅ Yes	❌ No	❌ No
protected	✅ Yes	❌ No	✅ Yes

Would you like to see examples with private and protected access specifiers next? 🚀