问题
How can I create std::list with a fixed element count?
回答1:
#include <list>
// list with 5 elements, using default constructor
const size_t fixedListSize(5);
std::list<int> mylist(fixedListSize);
If you want it to always have exactly 5 elements you'd have to wrap it in a facade class to prevent insertion and erasure.
If that is indeed what you want, you'd be better off using a different container instead of list, since as noted in other responses you would be hiding the most advantageous features of list.
回答2:
If you just want a fixed size container, maybe you are looking for std::tr1::array. (Or just std::array for C++0x.)
If you don't insert or remove elements I don't think there is any advantage in using std::list instead of std::array or std::vector.
回答3:
You should use std::list constructor.
explicit list (size_type n, const T& value = T(), const Allocator& = Allocator());
Just specify at time of creation exact count of elements.
std::list<int> someList(20);
You could specify initial value for each element too.
std::list<int> someList(20, int(42));
std::list::resize is the right solution too.
回答4:
I would have to ask you, why you want it to have a fixed number of elements and why use a list?
It could be that the user is implementing a cache with a limited number of elements and an LRU policy of removal. In that case a list is a good collection to use. Any time an element is accessed, you splice that element to the front of the list. If you need to insert a new elemenet (so the list gets full) you pop off the back of the list.
You can also maintain some kind of lookup for the elements but std::list is the best class to handle LRU.
来源：https://stackoverflow.com/questions/3907607/stdlist-fixed-size