Vector vs. List in the STL: When Should You Choose Which?

When to Choose Vector vs. List in the STL

According to Effective STL, the vector container should be the default choice for sequences. However, this recommendation requires further clarification.

Vector vs. List: Key Differences

To understand the distinction between vectors and lists, consider the following table:

Feature	Vector	List
Memory allocation	Contiguous	Non-contiguous
Storage overhead	Pre-allocates space	Constant memory overhead
Element space	No extra pointers	Extra space for node (pointers to next/previous)
Memory reallocation	Can reallocate memory for entire vector	Never reallocates memory for entire list
Insertion efficiency	O(1) at end, O(n) elsewhere	O(1) anywhere
Erasure efficiency	O(1) at end, O(n) elsewhere	O(1) always
Random access	Supported	Not supported
Iterator validity	Invalidated after additions/removals	Remains valid after additions/removals
Array access	Underlying array easily obtained	No underlying array available

When List May Be Preferable

While vectors are generally more efficient, lists can be a better choice in specific scenarios:

• When constant insertions and deletions occur anywhere in the sequence. Lists allow for O(1) insertions and erasures regardless of their position.
• When iterators need to remain valid despite modifications to the sequence: Lists' iterators remain valid after additions and removals, making them suitable for situations where iterating through a changing sequence is required.
• When combining lists is desired: Lists provide a convenient way to combine and splice multiple lists efficiently.
• When memory overhead is a concern: Lists have lower memory overhead than vectors, making them a good choice for scenarios where memory is constrained.

The above is the detailed content of Vector vs. List in the STL: When Should You Choose Which?. For more information, please follow other related articles on the PHP Chinese website!