#include <iostream>

int main() {
    // Array declaration and initialization
    int numbers[5] = {1, 2, 3, 4, 5};
    
    // Accessing array elements
    std::cout << "First element: " << numbers[0] << std::endl;
    std::cout << "Last element: " << numbers[4] << std::endl;
    
    // Modifying array elements
    numbers[2] = 10;
    std::cout << "Modified element: " << numbers[2] << std::endl;
    
    // Array traversal
    for (int i = 0; i < 5; i++) {
        std::cout << numbers[i] << " ";
    }
    std::cout << std::endl;
    
    return 0;
}

#include <iostream>

int main() {
    // 2D array declaration
    int matrix[3][3] = {
        {1, 2, 3},
        {4, 5, 6},
        {7, 8, 9}
    };
    
    // Accessing 2D array elements
    std::cout << "Element at [1][1]: " << matrix[1][1] << std::endl;
    
    // Printing 2D array
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            std::cout << matrix[i][j] << " ";
        }
        std::cout << std::endl;
    }
    
    return 0;
}

#include <iostream>
#include <vector>

int main() {
    // Vector declaration
    std::vector<int> vec;
    
    // Adding elements
    vec.push_back(10);
    vec.push_back(20);
    vec.push_back(30);
    
    // Accessing elements
    std::cout << "Size: " << vec.size() << std::endl;
    std::cout << "First element: " << vec[0] << std::endl;
    
    // Vector iteration
    for (int i = 0; i < vec.size(); i++) {
        std::cout << vec[i] << " ";
    }
    std::cout << std::endl;
    
    // Range-based for loop
    for (int num : vec) {
        std::cout << num << " ";
    }
    std::cout << std::endl;
    
    return 0;
}

#include <iostream>

int main() {
    int value = 42;
    int* ptr = &value;  // Pointer to value
    
    std::cout << "Value: " << value << std::endl;
    std::cout << "Address of value: " << &value << std::endl;
    std::cout << "Pointer value: " << ptr << std::endl;
    std::cout << "Dereferenced pointer: " << *ptr << std::endl;
    
    // Modifying value through pointer
    *ptr = 100;
    std::cout << "New value: " << value << std::endl;
    
    // Pointer arithmetic
    int numbers[] = {1, 2, 3, 4, 5};
    int* numPtr = numbers;
    
    std::cout << "First element: " << *numPtr << std::endl;
    std::cout << "Second element: " << *(numPtr + 1) << std::endl;
    
    return 0;
}

#include <iostream>

int main() {
    // Dynamic allocation
    int* dynamicArray = new int[5];
    
    // Initialize array
    for (int i = 0; i < 5; i++) {
        dynamicArray[i] = i + 1;
    }
    
    // Use array
    for (int i = 0; i < 5; i++) {
        std::cout << dynamicArray[i] << " ";
    }
    std::cout << std::endl;
    
    // Free memory
    delete[] dynamicArray;
    
    // Single dynamic variable
    int* singleValue = new int(25);
    std::cout << "Dynamic value: " << *singleValue << std::endl;
    delete singleValue;
    
    return 0;
}

#include <iostream>
#include <memory>

int main() {
    // Unique pointer
    std::unique_ptr<int> uniquePtr = std::make_unique<int>(42);
    std::cout << "Unique pointer value: " << *uniquePtr << std::endl;
    
    // Shared pointer
    std::shared_ptr<int> sharedPtr1 = std::make_shared<int>(100);
    std::shared_ptr<int> sharedPtr2 = sharedPtr1;
    
    std::cout << "Shared pointer 1: " << *sharedPtr1 << std::endl;
    std::cout << "Shared pointer 2: " << *sharedPtr2 << std::endl;
    std::cout << "Reference count: " << sharedPtr1.use_count() << std::endl;
    
    // Weak pointer
    std::weak_ptr<int> weakPtr = sharedPtr1;
    std::cout << "Weak pointer expired: " << weakPtr.expired() << std::endl;
    
    return 0;
}