set

问题 For some reason I am iterating over elements of a class in an std::set and would like to slightly modify the keys, knowing that the order will be unchanged. Iterators on std::set are const_iterators because if the key is modified, it might result in a bad order and therefore in set corruption. However I know for sure that my operations won't change the order of my elements in the set. For the moment, here is my solution: class Foo { public: Foo(int a, int b): a_(a),b_(b) {} ~Foo(){} bool

问题 Is there in the Standard Prelude functions which implement the union and the intersection of sets ? union :: (Eq a) => [a] -> [a] -> [a] intersect :: (Eq a) => [a] -> [a] -> [a] If no, may somebody can said if my implementation is efficient, (make good use of laziness and prelude function) unionSet :: (Eq a) => [a] -> [a] -> [a] unionSet as bs = foldl (\xs y -> if elem y xs then xs else xs ++ [y]) as bs intersectSet :: (Eq a) => [a] -> [a] -> [a] intersectSet as bs = let ns = [ a | a <- as,

问题 I'm looking every where on the web (dart website, stackoverflow, forums, etc), and I can't find my answer. So there is my problem: I need to write a function, that print a random sort of a list, witch is provided as an argument. : In dart as well. I try with maps, with Sets, with list ... I try the method with assert, with sort, I look at random method with Math on dart librabry ... nothing can do what I wana do. Can some one help me with this? Here some draft: var element03 = query('

问题 My understanding is the iterators of associative containers are not invalidated during insert or erase (unless the node pointed by iterator is erased). But in the below program the insert seems to invalidate the iterator. Is my understanding wrong? typedef std::set<unsigned int> myset_t; int main(int argc, char **argv) { myset_t rs; myset_t::reverse_iterator rit; myset_t::reverse_iterator srit; int ii = 500; rs.insert(10); rs.insert(11); rs.insert(12); rs.insert(13); rs.insert(14); rs.insert

问题 Is it possible to submit a form's data to a java Set in an action of Struts2? Action code: class TestAction extends ActionSupport{ private Set<Integer> mySet = new LinkedHashSet<Integer>(); public TestAction(){ } public String test(){ someMethod(mySet); } ... Getters/Setters ... } Form code: <form action="test.action" > <input name="mySet[0]" /> <input name="mySet[1]" /> <input name="mySet[2]" /> <submit /> </form> 回答1: The Set is just a collection, and Struts2 has support for any type of

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: How do you remove duplicates from a list in Python whilst preserving order? What I am trying to do is write a method that takes a list as an argument and uses a set to return a copy of the list where each element only occurs once, as well as having the elements in the new list occur in order of their first occurrence in the original list. I HAVE to use a set for this, however, I can't make it so that the output

问题 I'm new to C++. I'd like to know how experienced coders do this. what I have: set<int> s; s.insert(1); s.insert(2); s.insert(3); s.insert(4); s.insert(5); for(set<int>::iterator itr = s.begin(); itr != s.end(); ++itr){ if (!(*itr % 2)) s.erase(itr); } and of course, it doesn't work. because itr is incremented after it is erased. does it mean Itr has to point to the begin of the set everytime after i erase the element from the set? 回答1: for(set<int>::iterator itr = s.begin(); itr != s.end(); )

问题 Do erase call in std::set invalidate iterator ? As i have done below 5th from last line..? if yes what is better way to erase all elements from set class classA { public: classA(){}; ~classA(){}; }; struct structB { }; typedef std::set <classA*, structB> SETTYPE; typedef std::map <int, SETTYPE>MAPTYPE; int __cdecl wmain (int argc, wchar_t* pArgs[]) { MAPTYPE mapObj; /* ... .. Some Operation Here ... */ for (MAPTYPE::iterator itr1=mapObj.begin(); itr1!=mapObj.end(); itr1++) { SETTYPE li=(*itr1

问题 So I have a custom class Class that will have a set of another custom class Students. So it will look something like this: public class Class { private Set<Student> students; // other methods } Now I will be adding and removing many students to the set students and i will also be changing many of the private fields of a student already in the set of students. QUESTION: What data structure should I use to best implement this? Since I will be changing the property of the Student objects in set

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed last year . Is there an API for Set operations like Union, intersection, difference, Cartesian product, Function from a set to another, domain restriction and range restriction of those functions, .... in Java? Please comment on coverage (of operations) and performance. Thanks 回答1: Yes, the java Set class. Via Java SE