c++ 手写智能指针

以下是一个简单的C++手写智能指针的实现，它使用引用计数来跟踪指针的使用情况，确保在不再需要指针时正确地释放内存：

template <typename T>
class SmartPtr {
public:
    SmartPtr(T* ptr = nullptr) : ptr_(ptr) {
        if (ptr_) {
            shared_count_ = new int(1);
        }
    }

    ~SmartPtr() {
        release();
    }

    SmartPtr(const SmartPtr& other) {
        ptr_ = other.ptr_;
        if (ptr_) {
            shared_count_ = other.shared_count_;
            (*shared_count_)++;
        }
    }

    template <typename U>
    SmartPtr(const SmartPtr<U>& other) {
        ptr_ = other.get();
        if (ptr_) {
            shared_count_ = other.get_shared_count();
            (*shared_count_)++;
        }
    }

    SmartPtr& operator=(const SmartPtr& other) {
        if (this != &other) {
            release();
            ptr_ = other.ptr_;
            if (ptr_) {
                shared_count_ = other.shared_count_;
                (*shared_count_)++;
            }
        }
        return *this;
    }

    T& operator*() const {
        return *ptr_;
    }

    T* operator->() const {
        return ptr_;
    }

    T* get() const {
        return ptr_;
    }

    int use_count() const {
        return *shared_count_;
    }

    int* get_shared_count() const {
        return shared_count_;
    }

    void reset(T* ptr = nullptr) {
        release();
        ptr_ = ptr;
        if (ptr_) {
            shared_count_ = new int(1);
        }
    }

private:
    void release() {
        if (ptr_ && --(*shared_count_) == 0) {
            delete ptr_;
            delete shared_count_;
        }
    }

    T* ptr_;
    int* shared_count_;
};