Private Access Specifier in C++

 

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In C++, the private access specifier restricts access to class members, making them accessible only within the class. This ensures data security and encapsulation, preventing direct modification from outside the class.

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1️⃣ Syntax of private Access Specifier

• class ClassName {

• private:

•     // Private members (accessible only inside the class)

•     int data;

•     

•     void privateFunction() {

•         cout << "This is a private function." << endl;

•     }

• };

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2️⃣ Example: Private Members in a Class

• #include <iostream>

• using namespace std;

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• class BankAccount {

• private:

•     double balance;  // Private variable

• 
  

• public:

•     void setBalance(double b) {  // Public method to modify balance

•         if (b >= 0)

•             balance = b;

•     }

• 
  

•     double getBalance() {  // Public method to access balance

•         return balance;

•     }

• };

• 
  

• int main() {

•     BankAccount account;

•     

•     // account.balance = 1000;  // ❌ Error: Cannot access private member

•     account.setBalance(1000);   // ✅ Allowed via public function

• 
  

•     cout << "Balance: $" << account.getBalance() << endl;

•     return 0;

• }

Output:

• Balance: $1000

Explanation:

• Direct access to balance is not allowed because it's private.

• setBalance() and getBalance() act as getter and setter functions to modify and retrieve the value safely.

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3️⃣ Key Characteristics of private Access Specifier

Feature	Description
Visibility	Private members are accessible only within the class.
Encapsulation	Prevents unintended modifications from outside the class.
Inheritance Effect	Private members are not accessible in derived classes.

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4️⃣ Private Access in Inheritance

When a class is inherited, private members do not become accessible in the child class, but they still exist in the memory.

Example: Private Members Are Not Inherited

• #include <iostream>

• using namespace std;

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• class Parent {

• private:

•     int secret = 42;  // Private member

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• public:

•     int getSecret() {  // Public function to access private member

•         return secret;

•     }

• };

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• class Child : public Parent {

•     // secret is not accessible here

• };

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• int main() {

•     Child obj;

•     // cout << obj.secret;  // ❌ Error: Private member is inaccessible

•     cout << "Secret: " << obj.getSecret() << endl;  // ✅ Accessed via public function

•     return 0;

• }

Output:

• Secret: 42

Explanation:

• secret is private in Parent, so it cannot be accessed in Child.

• getSecret() provides controlled access to secret.

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5️⃣ When to Use private Access Specifier?

✅ To protect sensitive data from direct modification.
✅ To enforce encapsulation, allowing access only through controlled methods.
✅ When implementing internal helper functions that should not be exposed.

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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 protected access specifier next? 🚀

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