how could I tell STL, specifically for the method resize() in vector, to initialize objects with a constructor other than default, and with which parameters? I mean: class something { int a; something (int value); } std::vector<something> many_things; many_things.resize (20); more generally, how could I force STL to use my ...
Hi, I'm using VS2005 and the MS implementation of STL. However, the class type_info in is declared outside of "namespace std". This creates some problems for third party libs that excepts to find a std::type_info. Why is this so, and is there any workaround? Here is a sample from the beginning of typeinfo: class type_info { ... }; _S...
I was looking at a job posting recently and one of the requirements was that a person be a 9/10 in their knowledge of STL. When I judge my skills, to me a 10 is someone that writes advanced books on the subject, such as Jon Skeet (C#), John Resig (JavaScript) or Martin Odersky (Scala). So, a 9/10 is basically a 10, so I am not certain ...
I know STL containers like vector copies the object when it is added. push_back method looks like: void push_back ( const T& x ); I am surprised to see that it takes the item as reference. I wrote a sample program to see how it works. struct Foo { Foo() { std::cout << "Inside Foo constructor" << std::endl; } Foo...
I have a large vector (10^9 elements) of chars, and I was wondering what is the fastest way to write such vector to a file. So far I've been using next code: vector<char> vs; // ... Fill vector with data ofstream outfile("nanocube.txt", ios::out | ios::binary); ostream_iterator<char> oi(outfile, '\0'); copy(vs.begin(), vs.end(), oi); ...
Hello, I have blocks of data associated with latitude/longitude values. I'd like to create a lookup key/hash value from the latitude/longitude value so it can be used as a lookup into a map or something similar. I'm using negative values for West and South... therefore 5W, 10S is represented as -5, -10 in the program. I'd like to...
How do you check that an element is in a set? Is there a simpler equivalent of the following code: myset.find(x) != myset.end() ...
how can i get the type of the elements that are held by a STL container? ...
I was curious about STL implementations outside of what's packaged with gcc or Visual Studio, so a quick Google search turned up a few results, such as: Apache stdcxx uSTL rdeSTL Under what circumstances should one use an alternative standard template library? For instance, Apache's page has a list including items such as "full conf...
Hello Gurus, Yesterday evening I was using std::vector for my work, and this question popped into my mind: how does vector gives random access? I tried to look into code but was unsuccessful. Can anyone give some pointers? Thanks, Arun ...
I have a list of random integers. I'm wondering which algorithm is used by the list::sort() method. E.g. in the following code: list<int> mylist; // ..insert a million values mylist.sort(); EDIT: See also this more specific question. ...
Note: I accidentally posted this question without specifying which STL implementation I was using, and I felt it can't really be updated since it would render most of its answers obsolete. So, the correct question goes - which sorting algorithm is used in the below code, assuming I'm using the STL library of Microsoft Visual C++?: list...
Let's say I need to retrieve the median from a sequence of 1000000 random numeric values. If using anything but STL::list, I have no (built-in) way to sort sequence for median calculation. If using STL::list, I can't randomly access values to retrieve middle (median) of sorted sequence. Is it better to implement sorting myself and go...
Hello, after some years in Java and C# now I'm back to C++. Of course my programming style is influenced by those languages and I tend to feel the need of a special component that I used massively: the HASH MAP. In STL there is the hash_map, that GCC says it's deprecated and I should use unordered_map. So I turned to it. I confess I'm n...
This is probably best stated as an example. I have two vectors/lists: People = {Anne, Bob, Charlie, Douglas} Ages = {23, 28, 25, 21} I want to sort the People based on their ages using something like sort(People.begin(), People.end(), CustomComparator), but I don't know how to write the CustomComparator to look at Ages rather than...
We're using STLPORT and we'd like to change stlport's default allocator: instead of vector<int>, we'd like to try vector<int, otherallocator> Which alternative allocator are available in stlport, and what are their features? How do I use them? ...
Hi, I'd like to use std::copy to insert elements into a queue like this: vector<int> v; v.push_back( 1 ); v.push_back( 2 ); queue<int> q; copy( v.begin(), v.end(), insert_iterator< queue<int> >( q, q.front() ) ); But this fails to compile, complaining that 'begin' is not a member of 'std::queue'. Note: I tried it with std::inserter...
I wrote an OutputIterator for an answer to another question. Here it is: #include <queue> using namespace std; template< typename T, typename U > class queue_inserter { queue<T, U> &qu; public: queue_inserter(queue<T,U> &q) : qu(q) { } queue_inserter<T,U> operator ++ (int) { return *this; } queue_inserter<T,U> operat...
I have been searching for sample code creating iterator for my own container, but I haven't really found a good example. I know this been asked before (http://stackoverflow.com/questions/148540/c-creating-my-own-iterators) but didn't see any satisfactory answer with examples. I am looking for simple sample code to start how to design ...
Searching in the second value of a map i use somthing like the following: typedef std::map<int, int> CMyList; static CMyList myList; template<class t> struct second_equal { typename typedef t::mapped_type mapped_type; typename typedef t::value_type value_type; second_equal(mapped_type f) : v(f) {}; bool operator()(co...