STL中的向量和列表

我注意到在有效的STL

向量是这样一种序列默认情况下应该使用。

这是什么意思?似乎忽略效率向量可以做任何事情。

谁能给我一个场景，其中向量不是一个可行的选择，但必须使用列表?

当前回答

如果你不需要经常插入元素，那么向量会更有效。它具有比列表更好的CPU缓存位置。换句话说，访问一个元素使得下一个元素很有可能存在于缓存中，并且可以在不读取慢速RAM的情况下被检索。

2010-02-05 18:05:05

其他回答

在向量和列表的情况下，对我来说，主要的区别如下:

向量

A vector stores its elements in contiguous memory. Therefore, random access is possible inside a vector which means that accessing an element of a vector is very fast because we can simply multiply the base address with the item index to access that element. In fact, it takes only O(1) or constant time for this purpose. Since a vector basically wraps an array, every time you insert an element into the vector (dynamic array), it has to resize itself by finding a new contiguous block of memory to accommodate the new elements which is time-costly. It does not consume extra memory to store any pointers to other elements within it.

list

A list stores its elements in non-contiguous memory. Therefore, random access is not possible inside a list which means that to access its elements we have to use the pointers and traverse the list which is slower relative to vector. This takes O(n) or linear time which is slower than O(1). Since a list uses non-contiguous memory, the time taken to insert an element inside a list is a lot more efficient than in the case of its vector counterpart because reallocation of memory is avoided. It consumes extra memory to store pointers to the element before and after a particular element.

因此，记住这些区别，我们通常会考虑内存、频繁的随机访问和插入来决定给定场景中向量和列表的胜者。

2019-10-30 07:36:07

List是双链表，所以很容易插入和删除一个元素。我们只需要改变这几个指针，而在向量中如果我们想在中间插入一个元素那么它后面的每个元素都要移动一个下标。此外，如果向量的大小已满，那么它必须首先增加它的大小。所以这是一个昂贵的手术。因此，在这种情况下，只要需要更频繁地执行插入和删除操作，就应该使用案例列表。

2020-05-01 10:56:18

任何时候都不能使迭代器失效。

2010-02-05 17:57:22

std::vector	std::list
Contiguous memory.	Non-contiguous memory.
Pre-allocates space for future elements, so extra space required beyond what's necessary for the elements themselves.	No pre-allocated memory. The memory overhead for the list itself is constant.
Each element only requires the space for the element type itself (no extra pointers).	Each element requires extra space for the node which holds the element, including pointers to the next and previous elements in the list.
Can re-allocate memory for the entire vector any time that you add an element.	Never has to re-allocate memory for the whole list just because you add an element.
Insertions at the end are constant, amortized time, but insertions elsewhere are a costly O(n).	Insertions and erasures are cheap no matter where in the list they occur.
Erasures at the end of the vector are constant time, but for the rest it's O(n).	It's cheap to combine lists with splicing.
You can randomly access its elements.	You cannot randomly access elements, so getting at a particular element in the list can be expensive.
Iterators are invalidated if you add or remove elements to or from the vector.	Iterators remain valid even when you add or remove elements from the list.
You can easily get at the underlying array if you need an array of the elements.	If you need an array of the elements, you'll have to create a new one and add them all to it, since there is no underlying array.

一般来说，当你不关心你使用的是哪种类型的顺序容器时，使用vector，但如果你在容器的任何地方做很多插入或擦除，而不是在末尾，你就会想要使用list。如果你需要随机访问，你就需要向量，而不是列表。除此之外，在某些情况下，根据应用程序需要其中一个或另一个，但一般来说，这些都是很好的指导原则。

2010-02-05 18:53:43

〇简单一点在一天结束的时候，当你在c++中选择容器时感到困惑时，使用下面的流程图图像(对我说谢谢):-

向量,

Vector基于传染性记忆矢量是小数据集的一种方式 Vector在遍历数据集时执行最快向量插入删除在巨大数据集上很慢，但在非常数据集上很快小

列表,

List基于堆内存列表是非常庞大的数据集 List在遍历小数据集时相对较慢，但在巨大的气候资料列表插入删除在大数据集上速度快，但在小数据集上速度慢的

2019-10-30 07:53:40

STL中的向量和列表

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