Encapsulation

Overview

Encapsulation is the concept of bundling data and methods together and hiding the internal state of the object (`private` variables). This protects data from accidental corruption and makes code easier to refactor.

Syntax

cpp

class Thermostat {
private:
    int temperature; // Hidden data

public:
    void setTemp(int t) {
        if (t >= 60 && t <= 90) { // Validation logic protects the state
            temperature = t;
        }
    }
};

Common Pitfalls

Returning a non-const pointer or reference to a private variable, which breaks encapsulation by allowing outsiders to modify it directly.

Interview Tips

Encapsulation != Abstraction. Encapsulation is about 'hiding internal state' (private variables). Abstraction is about 'hiding complexity' (exposing only simple methods).

Real-World Example

Protecting a Bank Account balance.

example

cpp

/*
If balance was public:
account.balance = -9999; // Total system collapse

With Encapsulation:
void withdraw(int amount) {
    if (amount > 0 && balance >= amount) {
        balance -= amount;
    }
}
*/

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