deque

问题 I am working on a project with a library and I must work with unions. Specifically I am working with SDL and the SDL_Event union. I need to make copies of the SDL_Events, and I could find no good information on overloading assignment operators with unions. Provided that I can overload the assignment operator, should I manually sift through the union members and copy the pertinent members or can I simply come some members (this seems dangerous to me), or maybe just use memcpy() (this seems

问题 I have had to change from python 2.7 to 2.6. I've been using a deque with the maxlen property and have been checking what the maxlen is. Apparently you can use maxlen in python 2.6, but in 2.6 deques do not have a maxlen attribute. What is the cleanest way to check what the maxlen of a deque is in python 2.6? In 2.7: from collections import deque d = deque(maxlen = 10) print d.maxlen In 2.6 the deque can be used and the maxlen works properly, but maxlen is not an attribute that can be

问题 I have a problem I am working on where I need to use some sort of 2 dimensional array. The array is fixed width (four columns), but I need to create extra rows on the fly. To do this, I have been using vectors of vectors, and I have been using some nested loops that contain this: array.push_back(vector<float>(4)); array[n][0] = a; array[n][1] = b; array[n][2] = c; array[n][3] = d; n++ to add the rows and their contents. The trouble is that I appear to be running out of memory with the number

问题 Suppose I have li = iter([1,2,3,4]) . Will the garbage collector drop the references to inaccessible element when I do next(li) . And what about deque , will elements in di = iter(deque([1,2,3,4])) be collectable once consumed. If not, does a native data structure in Python implement such behaviour. 回答1: https://github.com/python/cpython/blob/bb86bf4c4eaa30b1f5192dab9f389ce0bb61114d/Objects/iterobject.c A reference to the list is held until you iterate to the end of the sequence. You can see

问题 I was looking at the java implementation of LinkedList, and found this: public class LinkedList<E> extends AbstractSequentialList<E> implements List<E>, Deque<E>, Cloneable, java.io.Serializable Why should a LinkedList support the Deque interface? I understand the desire to add elements to the end of the linked list, but those methods should have been incuded in the List interface. 回答1: The LinkedList implementation happens to to satisfy the Deque contract, so why not make it implement the

问题 I have a 'list' of objects, from which I want to take object at random position and push it on front of this list. Only this kind of operation will be performed. So I don't need a fast access to end of the list, only to it's front and average access to any other place. Which container would be the best for this? I was thinking about std::vector , but I've read that insert operation is not efficient. Then I came up with std::deque because of it's fast access to front, but what about efficiency

问题 Hi I need an stl container which can be indexed like a vector but does not move old elements in the memory like a vector would do with resize or reserve (Unless I call reserve once at the beginning with a capacity enough for all elements, which is not good for me). (Note I do address binding to the elements so I expect the address of these elements to never change). So I've found this deque. Do you think it is good for this purpose? Important: I need only pushback but I need to grow the

问题 I am creating the cell programatically using the reuse identifier. Note - I am not using storyboard for creating the cell Whenever the cell is dequeued, the cell is nil, so the cell needs to be newly created using alloc, which is expensive. EDIT (added 1 more question and corrected code) Question Why does this dequeue always return nil ? How can I correct it ? Does dequeue work only when used along with storyboard / nib file ? Code - (UITableViewCell *)tableView:(UITableView *)tableView

问题 I am almost certain this should be a duplicate but I searched for some time and could not find the answer. What should I use in C# to replace C++ vector and deque efficiently . That is I need a structure that supports direct indexing effieciently and also supports delete from one or both ends(depending on vector or deque case) again in an efficient manner. In java I usually use ArrayList at least for vector but for C# I found this source that states: ArrayList resizes dynamically. As elements

问题 I'm using a std::deque to store a fairly large number of objects. If I remove a bunch of those objects, it appears to me that its memory usage does not decrease, in a similar fashion to std::vector. Is there a way to reduce it? I know that in a vector you have to use the 'swap trick', which I assume would work here too, but I'd rather avoid that since it would require copying all the elements left in the container (and thus requires that you have enough memory to store every object twice). I