Getter & Setter, this Keyword in C++

 

1️⃣ What are Getters and Setters?

Getters and Setters are special functions in C++ that control access to private data members of a class.

• Getter (get() function) retrieves the value of a private variable.
• Setter (set() function) modifies the value of a private variable with validation if needed.

🔹 Why use Getters and Setters?

✔ Encapsulation – Keeps data secure by preventing direct access.
✔ Validation – Ensures data integrity before modification.
✔ Controlled Access – Allows read-only or write-only permissions.

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2️⃣ Example: Getters & Setters in C++

#include <iostream>
using namespace std;

class Student {
private:
    string name;
    int age;

public:
    // Setter function (modifies private variables)
    void setName(string n) {
        name = n;
    }

    void setAge(int a) {
        if (a > 0)  // Validation
            age = a;
        else
            cout << "Age must be positive!" << endl;
    }

    // Getter function (retrieves private variables)
    string getName() {
        return name;
    }

    int getAge() {
        return age;
    }
};

int main() {
    Student s;
    s.setName("Alice");
    s.setAge(20);

    cout << "Student Name: " << s.getName() << endl;
    cout << "Student Age: " << s.getAge() << endl;

    return 0;
}

🔹 Output

Student Name: Alice
Student Age: 20

✅ Encapsulation achieved – Direct access to name and age is not allowed.

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3️⃣ this Keyword in C++

The this keyword in C++ is a pointer that refers to the current object inside a class.

🔹 Why use this?

✔ Differentiates between instance variables and method parameters if they have the same name.
✔ Returns the current object’s address, allowing method chaining.

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4️⃣ Example: Using this to Differentiate Variables

#include <iostream>
using namespace std;

class Employee {
private:
    string name;
    int salary;

public:
    // Setter with 'this' pointer
    void setInfo(string name, int salary) {
        this->name = name;  // 'this' differentiates instance variable from parameter
        this->salary = salary;
    }

    void display() {
        cout << "Employee Name: " << name << ", Salary: " << salary << endl;
    }
};

int main() {
    Employee e;
    e.setInfo("John", 50000);
    e.display();

    return 0;
}

🔹 Output

Employee Name: John, Salary: 50000

✅ Why use this->name = name;?

• Without this->, C++ assumes both variables refer to the method parameter.
• this-> ensures we are assigning the value to the class variable.

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5️⃣ Example: this for Method Chaining

Method chaining allows multiple function calls on the same object in a single statement.

#include <iostream>
using namespace std;

class Person {
private:
    string name;
    int age;

public:
    Person* setName(string name) {
        this->name = name;
        return this;  // Returns current object
    }

    Person* setAge(int age) {
        this->age = age;
        return this;  // Returns current object
    }

    void display() {
        cout << "Name: " << name << ", Age: " << age << endl;
    }
};

int main() {
    Person p;
    p.setName("David")->setAge(25)->display();  // Method Chaining

    return 0;
}

🔹 Output

Name: David, Age: 25

✅ Method chaining improves readability by avoiding multiple statements.

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6️⃣ Key Takeaways

✔ Getters & Setters provide controlled access to private data.
✔ Encapsulation prevents direct modification of sensitive data.
✔ this pointer refers to the current object inside a class.
✔ Method chaining allows multiple function calls in a single line.

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