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  • How to print all values of Vector[]

    - by terence6
    I have a Vector[] of Object type that stores my data. How to print all it's objects ? The code: private static Vector<Object[]> vector = new Vector<Object[]>(); int event=0; for(int i=0; i<10; i++){ vector.add( this.addToObject(System.currentTimeMillis(), event , "String") ); event++; } private Object[] addToObject(long t, int i,String s ){ Object[] o = new Object[4]; o[3] = s; o[2] = i; o[1] = "00000"; o[0] = t; return o; } printing public static void main(String[]args){ main m = new Main(); for(int i=0; i< m.vector.size(); i++){ } } And I'd like to get sth like this : 1202393057117 1 OOOOO String 1202393057117 2 OOOOO String 1202393057118 3 OOOOO String 1202393057118 4 OOOOO String 1202393057118 5 OOOOO String

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  • functor returning 0

    - by Jon
    I've recently started teaching myself the standard template library. I was curious as to why the GetTotal() method in this class is returning 0? ... class Count { public: Count() : total(0){} void operator() (int val){ total += val;} int GetTotal() { return total;} private: int total; }; void main() { set<int> s; Count c; for(int i = 0; i < 10; i++) s.inset(i); for_each(s.begin(), s.end(), c); cout << c.GetTotal() << endl; }

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  • Vector [] vs copying

    - by sak
    What is faster and/or generally better? vector<myType> myVec; int i; myType current; for( i = 0; i < 1000000; i ++ ) { current = myVec[ i ]; doSomethingWith( current ); doAlotMoreWith( current ); messAroundWith( current ); checkSomeValuesOf( current ); } or vector<myType> myVec; int i; for( i = 0; i < 1000000; i ++ ) { doSomethingWith( myVec[ i ] ); doAlotMoreWith( myVec[ i ] ); messAroundWith( myVec[ i ] ); checkSomeValuesOf( myVec[ i ] ); } I'm currently using the first solution. There are really millions of calls per second and every single bit comparison/move is performance-problematic.

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  • Iterator not accessible because of private inheritance

    - by Bo Tian
    I've created a new class that composes std::deque by private inheritance, i.e, class B : private std::deque<A> { ... }; and in my source code I tried to use iterator of B, i.e., B::iterator it The compiler error is error C2247: 'std::deque<_Ty>::iterator' not accessible because 'B' uses 'private' to inherit from 'std::deque<_Ty>' So the question is, how can I make the iterator accessible?

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  • Access to map data

    - by herzl shemuelian
    I have a complex map that defined typedef short short1 typedef short short2 typedef map<short1,short2> data_list; typedef map<string,list> table_list; I have a class that fill table_list class GroupingClass { table_list m_table_list; string Buildkey(OD e1){ string ostring; ostring+=string(e1.m_Date,sizeof(Date)); ostring+=string(e1.m_CT,sizeof(CT)); ostring+=string(e1.m_PT,sizeof(PT)); return ostring; } void operator() (const map<short1,short2>::value_type& myPair) { OptionsDefine e1=myPair.second; string key=Buildkey(e1); m_table_list[key][e1.m_short2]=e1.m_short2; } operator table_list() { return m_table_list; } }; and I use it by table_list TL2 GroupingClass gc; TL2=for_each(mapOD.begin(), mapOD.end(), gc); but when I try to access to internal map I have problems for example data_list tmp; tmp=TL2["AAAA"]; short i=tmp[1]; //I dont update i variable but if i use a loop by itrator this work properly why this no work at first way thanks herzl

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  • Can I use vector as index in map structure in c++?

    - by tsubasa
    I attempted to do something like this but it does not compile: class point { public: int x; int y; }; int main() { vector<point> vp1; vector<point> vp2; vector<point> vp3; map < vector<point>, int > m; m[vp1] = 1; m[vp2] = 2; m[vp3] = 3; map < vector<point>, int >::iterator it; for (it=m.begin(); it!=m.end(); it++) { cout<<m[it->first]<<endl; } return 0; }

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  • Best way to insert items from a Derived class's constructor into a Base class's private std::vector?

    - by Will
    I have these classes: class Base { ... private: std::vector<X> v; }; class Derived { Derived(X*, int n); } where the constructor of Derived is passed an array of item Xs, which I need to insert into my vector v in the Base class. (X is a smart pointer) Currently I see two ways to do this: 1) Create a function in Base: InsertItem(X*) that will insert an item into the vector. 2) Create a vector in Derived that contains the full list, then get it into Base by moving the entire vector. I dont see any advantages to #2, but was wondering if #1 was a good solution, or if there are better ways to do this. Thanks!

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  • How are iterators and pointers related?

    - by sharptooth
    Code with iterators looks pretty much like code with pointers. Iterators are of some obscure type (like std::vector<int>::iterator for example). What I don't get is how iterators and pointer are related to each other - is an iterator a wrapper around a pointer with overloaded operations to advance to adjacent elements or is it something else?

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  • Java 7 API design best practice - return Array or return Collection

    - by Shengjie
    I know this question has be asked before generic comes out. Array does win out a bit given Array enforces the return type, it's more type-safe. But now, with latest JDK 7, every time when I design this type of APIs: public String[] getElements(String type) vs public List<String> getElements(String type) I am always struggling to think of some good reasons to return A Collection over An Array or another way around. What's the best practice when it comes to the case of choosing String[] or List as the API's return type? Or it's courses for horses. I don't have a special case in my mind, I am more looking for a generic pros/cons comparison.

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  • Multiple indexes for a Java Collection - most basic solution?

    - by chris_l
    Hi, I'm looking for the most basic solution to create multiple indexes on a Java Collection. Required functionality: When a Value is removed, all index entries associated with that value must be removed. Index lookup must be faster than linear search (at least as fast as a TreeMap). Side conditions: It should ideally work with JavaSE (6.0) alone - no extra libraries, if possible. If necessary, then only small (not something like Lucene), common and well tested libraries. No database! Of course, I could write a class that manages multiple Maps myself. But I'd like to know, if it can be done without - while still getting a simple usage similar to using a single indexed java.util.Map. Thanks, Chris

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  • How to implement a collection (list, map?) of complicated strings in Java?

    - by Alex Cheng
    Hi all. I'm new here. Problem -- I have something like the following entries, 1000 of them: args1=msg args2=flow args3=content args4=depth args6=within ==> args5=content args1=msg args2=flow args3=content args4=depth args6=within args7=distance ==> args5=content args1=msg args2=flow args3=content args6=within ==> args5=content args1=msg args2=flow args3=content args6=within args7=distance ==> args5=content args1=msg args2=flow args3=flow ==> args4=flowbits args1=msg args2=flow args3=flow args5=content ==> args4=flowbits args1=msg args2=flow args3=flow args6=depth ==> args4=flowbits args1=msg args2=flow args3=flow args6=depth ==> args5=content args1=msg args2=flow args4=depth ==> args3=content args1=msg args2=flow args4=depth args5=content ==> args3=content args1=msg args2=flow args4=depth args5=content args6=within ==> args3=content args1=msg args2=flow args4=depth args5=content args6=within args7=distance ==> args3=content I'm doing some sort of suggestion method. Say, args1=msg args2=flow args3=flow == args4=flowbits If the sentence contains msg, flow, and another flow, then I should return the suggestion of flowbits. How can I go around doing it? I know I should scan (whenever a character is pressed on the textarea) a list or array for a match and return the result, but, 1000 entries, how should I implement it? I'm thinking of HashMap, but can I do something like this? <"msg,flow,flow","flowbits" Also, in a sentence the arguments might not be in order, so assuming that it's flow,flow,msg then I can't match anything in the HashMap as the key is "msg,flow,flow". What should I do in this case? Please help. Thanks a million!

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  • How do I force my std::map to deallocate memory used?

    - by monkeyking
    I'm using a std::map, and I can't seem to free the memory back to the OS. It looks like, int main(){ aMap m; while(keepGoing){ while(fillUpMap){ //populate m } doWhatIwantWithMap(m); m.clear(); //flush some buffered values into map for next iteration flushIntoMap(m); } } Each (fillUpmap) allocates around 1gig, so I'm very much interested in getting this back to my system before it eats up all my memory. Ive experienced the same with std::vector, but there I could force it to free by doing a swap with an empty std::vector. This doesn't work with map. When I use valgrind it says that all memory is freed, so its not a problem with a leak, since everything is cleared up nicely after a run.

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  • Why is TreeSet<T> an internal type in .NET?

    - by Justin Niessner
    So, I was just digging around Reflector trying to find the implementation details of HashSet (out of sheer curiosity based on the answer to another question here) and noticed the following: internal class TreeSet<T> : ICollection<T>, IEnumerable<T>, ICollection, IEnumerable, ISerializable, IDeserializationCallback Without looking too deep into the details, it looks like a Self-Balancing Binary Search Tree. My question is, is there anybody out there with the insight as to why this class is internal? Is it simply because the other collection types use it internally and hide the complexities of a BST from the general masses...or am I way off base?

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  • std::map insert segmentation fault

    - by Jakub Czaplicki
    Why does this code stop with segmentation fault : class MapFile { public: /* ... */ std::map <unsigned int, unsigned int> inToOut; }; bool MapFile::LoadMapFile( const wxString& fileName ) { /* ... */ inToOut.insert( std::make_pair(input,output) ); } but this one works fine : class MapFile { public: /* ... */ }; bool MapFile::LoadMapFile( const wxString& fileName ) { /* ... */ std::map <unsigned int, unsigned int> inToOut; inToOut.insert( std::make_pair(input,output) ); } ?

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  • C++'s std::string pools, debug builds? std::string and valgrind problems

    - by Den.Jekk
    Hello, I have a problem with many valgrind warnings about possible memory leaks in std::string, like this one: 120 bytes in 4 blocks are possibly lost in loss record 4,192 of 4,687 at 0x4A06819: operator new(unsigned long) (vg_replace_malloc.c:230) by 0x383B89B8B0: std::string::_Rep::_S_create(unsigned long, unsigned long, std::allocator<char> const&) (in /usr/lib64/libstdc++.so.6.0.8) by 0x383B89C3B4: (within /usr/lib64/libstdc++.so.6.0.8) by 0x383B89C4A9: std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char const*, unsigned long, std::allocator<char> const&) (in /usr/lib64/libstdc++.so.6.0.8) I'm wondering: does std::string (GCC 4.1.2) use any memory pools? if so, is there any way to disable the pools (in form of a debug build etc.)? Regards, Den

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  • Choosing design method for ladder-like word game.

    - by owca
    I'm trying to build a simple application, with the finished program looking like this : I will also have to implement two different GUI layouts for this. Now I'm trying to figure out the best method to perform this task. My professor told me to introduce Element class with 4 states : - empty - invisible (used in GridLayout) - first letter - other letter I've thought about following solutions (by List I mean any sort of Collection) : 1. Element is a single letter, and each line is Element[]. Game class will be array of arrays Element[]. I guess that's the dumbest way, and the validation might be troublesome. 2. Like previously but Line is a List of Element. Game is an array of Lines. 3. Like previously but Game is a List of Lines. Which one should I choose ? Or maybe do you have better ideas ? What collection would be best if to use one ?

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  • Is there an equivalent for ActiveRecord#find_by equivalent for C#?

    - by Benjamin Manns
    I'm originally a C# developer (as a hobby), but as of late I have been digging into Ruby on Rails and I am really enjoying it. Right now I am building an application in C# and I was wondering if there is any collection implementation for C# that could match (or "semi-match") the find_by method of ActiveRecord. What I am essentially looking for is a list that would hold Rectangles: class Rectangle { public int Width { get; set; } public int Height { get; set; } public String Name { get; set; } } Where I could query this list and find all entries with Height = 10, Width = 20, or name = "Block". This was done with ActiveRecord by doing a call similar to Rectangle.find_by_name('Block'). The only way I can think of doing this in C# is to create my own list implementation and iterate through each item manually checking each item against the criteria. I fear I would be reinventing the wheel (and one of poorer quality). Any input or suggestions is much appreciated.

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  • Traversable => Java Iterator

    - by Andres
    I have a Traversable, and I want to make it into a Java Iterator. My problem is that I want everything to be lazily done. If I do .toIterator on the traversable, it eagerly produces the result, copies it into a List, and returns an iterator over the List. I'm sure I'm missing something simple here... Here is a small test case that shows what I mean: class Test extends Traversable[String] { def foreach[U](f : (String) => U) { f("1") f("2") f("3") throw new RuntimeException("Not lazy!") } } val a = new Test val iter = a.toIterator

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  • Accessing a struct collection property from within another collection

    - by paddyb
    I have a struct that I need to store in a collection. The struct has a property that returns a Dictionary. public struct Item { private IDictionary<string, string> values; public IDictionary<string, string> Values { get { return this.values ?? (this.values = new Dictionary<string, string>()); } } } public class ItemCollection : Collection<Item> {} When testing I've found that if I add the item to the collection and then try to access the dictionary the structs values property is never updated. var collection = new ItemCollection { new Item() }; // pre-loaded with an item collection[0].Values.Add("myKey", "myValue"); Trace.WriteLine(collection[0].Values["myKey"]); // KeyNotFoundException here However if I load up the item first and then add it to a collection the values field is maintained. var collection = new ItemCollection(); var item = new Item(); item.Values.Add("myKey", "myValue"); collection.Add(item); Trace.WriteLine(collection[0].Values["myKey"]); // ok I've already decided that a struct is the wrong option for this type, and when using a class the issue doesn't occur, but I'm curious what's different between the two methods. Can anybody explain what's happening?

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  • WPF - Dynamically access a specific item of a collection in XAML

    - by Andy T
    Hi, I have a data source ('SampleAppearanceDefinitions'), which holds a single collection ('Definitions'). Each item in the collection has several properties, including Color, which is what I'm interested in here. I want, in XAML, to display the Color of a particular item in the collection as text. I can do this just fine using this code below... Text="{Binding Source={StaticResource SampleAppearanceDefinitions}, Path=Definitions[0].Color}" The only problem is, this requires me to hard-code the index of the item in the Definitions collection (I've used 0 in the example above). What I want to do in fact is to get that value from a property in my current DataContext ('AppearanceID'). One might imagine the correct code to look like this.... Text="{Binding Source={StaticResource SampleAppearanceDefinitions}, Path=Definitions[{Binding AppearanceID}].Color}" ...but of course, this is wrong. Can anyone tell me what the correct way to do this is? Is it possible in XAML only? It feels like it ought to be, but I can't work out or find how to do it. Any help would be greatly appreciated! Thanks! AT

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  • Java Double entry table

    - by Tom
    Hi, Does anyone know a double entry table implementation in java I can download ? I need to do something like this 1 2 3 _______ a| x y z b| h l m c| o a k table.get(a,1) would return x Of course, it should use any Object as key, value, etc Thanks in advance

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  • Interview Question: .Any() vs if (.Length > 0) for testing if a collection has elements

    - by Chris
    In a recent interview I was asked what the difference between .Any() and .Length > 0 was and why I would use either when testing to see if a collection had elements. This threw me a little as it seems a little obvious but feel I may be missing something. I suggested that you use .Length when you simply need to know that a collection has elements and .Any() when you wish to filter the results. Presumably .Any() takes a performance hit too as it has to do a loop / query internally.

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