map

问题 I'm a new C++ programmer, I learned Java and ANSI C a time ago and decided to give it a shot. Well, I love C++, but I didn't like how the iterators work: In java, you could make a whole container private and implement a getter function to it's iterator, and the iterator has a method hasNext() that returns a boolean depending on if it has reached the end of the container. The only way I found to do something similar on C++ is writing 2 getters, iteratorBegin() and iteratorEnd() , that returned

问题 First of all I read all the previously asked questions related to this questions, but didn't able to solve my problem. I have one 3D Map, map<int,map<const char*, const char*>> map3D; map<const char*, const char*> submap; Now i inserted valued in it like this, the max of value of int is 5 but for each int value there is 50 key and value for submap. I inserted the value like this submap.insert(std::pair<const char*,const char*>(TempA, TempB)); map3D.insert(pair<int,map<const char*,const char*>

问题 I have declared map: std::map <std::string, int> mymap; I want to insert two values in above map *vit and hit->first and then sending and receiving via socket. My code: for (std::map < int, std::vector < std::string > >::iterator hit = three_highest.begin(); hit != three_highest.end(); ++hit) { for (std::vector < std::string >::iterator vit = (*hit).second.begin(); vit != (*hit).second.end(); vit++) { std::cout << hit->first << ":"; std::cout << *vit << "\n"; mymap.insert( std::pair<std:

问题 I'm writing a Windows Phone 8.1 app(Windows Runtime version), and I used the MapIcon class to place the icons on the map control. However, I hope these icons can react to the "click" event so that I could show more details after a user has clicked a specific icon. I googled and wasn't able to find an answer. Is it possible, or do I have to create my own class in order to achieve this goal(and how)? It's my first time to develop the Windows Phone 8.1 app, so any suggestions are really

问题 I would like to add a tile source which is basically 1 PNG with a size of 800x800. I created a subclass of RMAbstractWebMapSource implementing the methods below but it doesn't work and I get a log error 'The tile source ... has a different tile side length than the tilesource container'. @implementation CustomTileSource - (NSURL *)URLForTile:(RMTile)tile { return [[NSURL alloc] initWithString:@"THE_URL_OF_MY_PNG"]; } - (NSString *)uniqueTilecacheKey { return @"NLSMap"; } - (NSString *

问题 EDIT after answered: < should be provided for std::map . For more information about best practice, go for James McNellis's answer . The code included in this question is poorly written. It is just because I am playing with SPOJ and the input data is strictly valid. The std::string approach is what I chose at first, but it turned out to be not fast enough. Thank you. I know I cannot use char[] directly with map, such as map<char[], int> . Thus I put it in a class. But it still can go through

问题 I want to create a HashMap with RGB colors as keys. How should I store them to have best performance? I mean, how does the "speed" of a hashmap refer to the object type of the key? Should I use Integer (018052175) where each triplet would be one of RGB, String (1234AF) as HEX, or own Color class with int r, g, b ? What might be the fastest implementation? 回答1: The speed of hash map is constrained by several essential properties of the hashCode and equals functions: How easy it is to calculate

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Thread safety of std::map for read-only operations Having std::map a can we do a.find(...)->second in multiple threads at the same time on it? 回答1: Yes. As long as none of your threads do a write i.e. Construct the data structure in memory Use as many threads to find/read as you require. If the leaf needs altering put a mutex there. 来源： https://stackoverflow.com/questions/7198332/are-find-and-read-operations-on

问题 Having a set of data: {sentenceA1}{\t}{sentenceB1} {sentenceA1}{\t}{sentenceB2} {sentenceA2}{\t}{sentenceB1} {sentenceA3}{\t}{sentenceB1} {sentenceA4}{\t}{sentenceB2} I want to map a sentenceA to all the sentences that have a common sentenceB in Scala so the result will be something like this: {sentenceA1}->{sentenceA2,sentenceA3,sentenceA4} or {sentenceA2}->{sentenceA1, sentenceA3} 回答1: val lines = List( "sentenceA1\tsentenceB1", "sentenceA1\tsentenceB2", "sentenceA2\tsentenceB1",

问题 why does Guava doesn't have the following factory call to create a MultiMap from a normal Map? public static <K,V> MultiMap<K,V> invertMap(Map<V,K> map); I have program-names mapped to an integer of how often they were called. I'd like to invert this, so that i can ultimately construct a TreeMap, sorted by call-count, which then are the keys leading to one or multiple program-names. 回答1: How about: public static <K,V> Multimap<K,V> invertMap(Map<V,K> map) { return Multimaps.invertFrom