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
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。
其他回答
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。
任何时候都不能使迭代器失效。
保留迭代器的有效性是使用列表的原因之一。另一种情况是当你不希望在推送物品时重新分配向量。这可以通过巧妙地使用reserve()来管理，但在某些情况下，仅使用列表可能更容易或更可行。
在表格中总结答案以供快速参考:
| Vector | List | |
|---|---|---|
| Access | Faster | Slower |
| Insert/Delete Operations | Slower | Faster |
| Memory Allocation | Contiguous | Non-contiguous |
| Size Pre-allocation | Need to be reserved | Not necessary to reserve |
| Space Required Per Element | Only for the element itself | For element and pointers to next (and optionally previous elements) |
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。
