#include <iostream> // For standard input and output
using namespace std; // Allows use of standard library without std:: prefix

int main() {
    cout << "Hello, World!" << endl; // Prints message followed by a new line
    return 0; // Indicates successful execution
}

int a;
cin >> a; // Takes input from user and stores in 'a'
cout << "You entered: " << a << endl; // Prints the value of 'a'

int a = 10; // Integer variable
float b = 3.14f; // Floating-point variable
bool isAlive = true; // Boolean variable
string name = "Alice"; // String variable

if (a > 0) cout << "Positive";
else cout << "Non-positive";

for (int i = 0; i < 5; i++) {
    cout << i << endl;
}

int add(int a, int b) {
    return a + b;
}

int arr[5] = {1, 2, 3, 4, 5};
for (int i = 0; i < 5; i++) {
    cout << arr[i] << " "; // Prints elements of the array
}

string name = "Bob";
// cout << name << endl; // Prints the string
cout << name.length(); // Outputs length of the string

int matrix[2][3] = {{1, 2, 3}, {4, 5, 6}};

int a = 5;
int *p = &a; // Pointer to variable 'a'
cout << *p; // Dereferencing to get value

class Employee {
public:
    string name;
    int salary;
    Employee(string n, int s) {
        name = n;
        salary = s;
    }
};

class Animal {
public:
    void sound() {
        cout << "Animal sound";
    }
};

class Dog : public Animal {
public:
    void sound() {
        cout << "Bark";
    }
};

int main() {
    Animal* a;
    Dog d;
    a = &d;
    a->sound();  // Output: Animal sound (without virtual)
}

class Animal {
public:
    virtual void sound() {
        cout << "Animal sound";
    }
};

int* p = new int;
delete p;

int *p = new int; // Dynamic memory allocation
*p = 10; // Assign value
cout << *p; // Access value
delete p; // Free memory

#include <fstream>
ifstream file("file.txt");
char ch;
file >> ch;
file.close();

#include <fstream>
ofstream file("example.txt"); // Create file
file << "Hello, file!"; // Write to file
file.close(); // Close the file

class Node {
public:
    int data;
    Node* next;
};

#include <stack>
stack<int> s;
s.push(1);
s.pop();

class Node {
public:
    int data;
    Node* left;
    Node* right;
};

#include <iostream>
using namespace std;

class Student {
public:
    string name;
    int age;

    void introduce() {
        cout << "Hi, I am " << name << " and I am " << age << " years old." << endl;
    }
};

int main() {
    Student s1;
    s1.name = "Alice";
    s1.age = 20;
    s1.introduce();
    return 0;
}

class BankAccount {
private:
    int balance;

public:
    void deposit(int amount) {
        if (amount > 0)
            balance += amount;
    }

    int getBalance() {
        return balance;
    }
};

int main() {
    BankAccount account;
    account.deposit(1000);
    cout << "Balance: " << account.getBalance();
    return 0;
}

class Vehicle {
public:
    void start() {
        cout << "Vehicle starting..." << endl;
    }
};

class Car : public Vehicle {
public:
    void drive() {
        cout << "Driving the car" << endl;
    }
};

int main() {
    Car myCar;
    myCar.start();  // from Vehicle
    myCar.drive();  // from Car
    return 0;
}

class Animal {
public:
    virtual void speak() {
        cout << "Animal sound" << endl;
    }
};

class Dog : public Animal {
public:
    void speak() override {
        cout << "Bark" << endl;
    }
};

int main() {
    Animal* a;
    Dog d;
    a = &d;
    a->speak();  // Output: Bark
    return 0;
}

class Shape {
public:
    virtual void draw() = 0;  // Pure virtual function
};

class Circle : public Shape {
public:
    void draw() override {
        cout << "Drawing Circle" << endl;
    }
};

int main() {
    Shape* s = new Circle();
    s->draw();
    return 0;
}