What are some advanced examples of using unique pointers in C++?

What are some advanced examples of using unique pointers in C++?

Unique pointers are smart pointers that ensure exclusive ownership of a dynamically allocated object. Here are a few advanced examples:

1. Custom Deleters: You can provide a custom deleter to a unique pointer to control how the memory is released.

2. Unique Pointer Arrays: Using std::unique_ptr with arrays to manage dynamic arrays safely.

3. Factory Functions: Creating factory functions that return unique pointers to encapsulate object creation and ownership.

Would you like to see code examples for any of these?

Yes, please show me a code example for custom deleters.

Sure! Here's a simple example of using a custom deleter with a unique pointer:

#include <iostream>
#include <memory>

struct MyObject {
    MyObject() { std::cout << "MyObject created!" << std::endl; }
    ~MyObject() { std::cout << "MyObject destroyed!" << std::endl; }
};

int main() {
    auto customDeleter = [](MyObject* obj) {
        std::cout << "Custom deleter called!" << std::endl;
        delete obj;
    };

    std::unique_ptr<MyObject, decltype(customDeleter)> ptr(new MyObject(), customDeleter);
    return 0;
}

In this example, when the unique pointer goes out of scope, the custom deleter is called, allowing you to add additional cleanup logic if needed.

That's great! Can you also explain how to use unique pointers with arrays?

Absolutely! To use std::unique_ptr with arrays, you can specify the array type in the template parameter. Here's an example:

#include <iostream>
#include <memory>

int main() {
    std::unique_ptr<int[]> arr(new int[5]);

    for (int i = 0; i < 5; ++i) {
        arr[i] = i * 10;
    }

    for (int i = 0; i < 5; ++i) {
        std::cout << arr[i] << " ";
    }
    std::cout << std::endl;

    // No need to manually delete the array, unique_ptr takes care of it.
    return 0;
}

In this example, std::unique_ptr<int[]> manages a dynamic array of integers. When the unique pointer goes out of scope, it automatically deletes the array.