从共享指针向量字符串返回值

I'm trying to implement a return method for a class I want to use smart pointers. I have:

我正在尝试为我想要使用智能指针的类实现一个返回方法。我有:

std::shared_ptr<std::vector<std::string>> data;

I want to access its last value with this function:

我想用这个函数访问它的最后一个值:

std::string& rear()
    {

    };

How do I access values with the shared_ptr?

如何使用shared_ptr访问值?

2 个解决方案

#1

I think something like this:

我觉得这样的事情:

std::string& rear()
{
    assert(data.get() != 0 && !data->empty());
    return *(*data).rbegin();
};

*data is a vector

*数据是一个向量

(*data).rbegin() returns a reverse iterator pointing to the last element

(* data).rbegin()返回指向最后一个元素的反向迭代器

*(*data).rbegin() dereferences the iterator, getting its value (a reference)

*(* data).rbegin()取消引用迭代器,获取其值(引用)

#2

SImply return the last element from the array after dereferencing the pointer. The member function std::vector::back would return the element from the end of the vector which is also the last element.

在解除引用指针后,只返回数组中的最后一个元素。成员函数std :: vector :: back将从向量的末尾返回该元素,该向量也是最后一个元素。

It is worth noting, that smart pointers are pointer wrappers, which generally supports the operations that you would have done on C pointers, which includes dereferencing * and member access via dereferencing ->.

值得注意的是,智能指针是指针包装器,它通常支持您在C指针上执行的操作,包括解引用*和通过解除引用的成员访问 - >。

std::string& rear()
{
    if (data && ! data.empty ())
        return data->back();
    else
        // Your Error Handling Should Go Here
        ;
};

#1