Destructors

Overview

Destructors (`~ClassName`) are called automatically when an object goes out of scope or is deleted. They are essential for cleaning up resources like dynamic memory, closing files, or releasing locks (RAII).

Syntax

cpp

class FileHandler {
    int* data;
public:
    FileHandler() {
        data = new int[100]; // Allocate memory
    }
    
    // Destructor (starts with ~)
    ~FileHandler() {
        delete[] data; // Free memory!
        cout << "Resources cleaned up.";
    }
};

Common Pitfalls

Failing to write a destructor when your class allocates memory using `new`, resulting in severe memory leaks.

Interview Tips

Destructors take no arguments and return no type.
Explain RAII (Resource Acquisition Is Initialization). In C++, tying resource cleanup to object destructors guarantees that memory/files are freed even if an exception occurs.

Real-World Example

Automated cleanup when object dies.

example

cpp

#include <iostream>
using namespace std;

class Session {
public:
    Session() { cout << "Session Started\n"; }
    ~Session() { cout << "Session Ended (Cleanup)\n"; }
};

void runGame() {
    Session s; // Created here
    cout << "Playing...\n";
} // s goes out of scope here, Destructor runs!

int main() {
    runGame();
    return 0;
}

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