stdvector

I have a C# front end and a C++ backend for performance reasons. Now I would like to call a C++ function like for example: void findNeighbors(Point p, std::vector<Point> &neighbors, double maxDist); What I'd like to have is a C# wrapper function like: List<Point> FindNeigbors(Point p, double maxDist); I could pass a flat array like Point[] to the unmanaged C++ dll, but the problem is, that I don't know how much memory to allocate, because I don't know the number of elements the function will return... Is there an elegant way to handle this without having troubles with memory leaks? Thanks for

I know it's a bad habit, but I'd like to know some workaround or hack for this problem. I have a class like this: template <class T> class A : std::vector<T> { T& operator()(int index) { // returns a _reference_ to an object return this->operator[](index); } }; It's possible to do things like this: A<int> a{1,2,3,4}; a(3) = 10; But it stops working if somebody uses bool as a template parameter A<bool> a{true, false, true}; std::cout << a(0) << std::endl; // not possible if (a(1)) { /* something */ } // not possible std::vector<bool> is a specialized version of vector ( http://www.cplusplus.com

I am developing a multi threaded application, each thread will read (there will be no modifying of structures) from a group of maps and vectors. Can anyone please advise, since the threads are only reading from these structures would it be necessary to implement a sharable mutex around the code blocks where these structures are being read? alexrider In case of read only map/vector there is no need to use mutexes. This was already answered for both vector and map While C++03 doesn't mention threads, C++11 has clause covering you question. 23.2.2 Container data races [container.requirements

I am not sure what to make of this - please tell me what's wrong with the code below. I modified my code to reduce it to the simplest terms. There is a std::vector with a bunch of MyNode objects. The first step is to get a constant reference to one of the data elements of one of these nodes (Data m_data) - in the example below, there is only one node before the 2nd node is inserted as seen below: const cv::Data& currData = m_nodesVector[currIndex].GetData(); MyNode node(...); m_nodesVector.push_back(node); At exactly the vector::push_back call, the value of currData changes!! I just don't get

I have a function that takes a pointer to char array and segment size as input arguments and calls another function that requires a std::array<std::string> . The idea is that the input char array is "sectioned" into equal parts, and string array formed. The input char array format is several smaller arrays (or strings) of determined size, concatenated togeather. These are not assumed zero-terminated, although they might be. Examples for segment size 5 and number of elements 10: char k[] = "1234\0001234\0001234\0001234\0001234\0001234\0001234\0001234\0001234\0001234\000"; char m[] = "1234

I have two STL vectors A and B and I'd like to clear all elements of A and move all elements of B to A and then clear out B . Simply put, I want to do this: std::vector<MyClass> A; std::vector<MyClass> B; .... A = B; B.clear(); Since B could be pretty long, it takes k*O(N) to do this operation, where k is a constant, and N is max(size_of(A), size_of(B)) . I was wondering if there could be a more efficient way to do so. One thing that I could think of is to define A and B as pointers and then copy pointers in constant time and clear out B . Using C++11, it's as simple as: A = std::move(B); Now

This question already has an answer here: How to find out if an item is present in a std::vector? 18 answers Is there any built in function which tells me that my vector contains a certain element or not e.g. std::vector<string> v; v.push_back("abc"); v.push_back("xyz"); if (v.contains("abc")) // I am looking for one such feature, is there any // such function or i need to loop through whole vector? You can use std::find as follows: if (std::find(v.begin(), v.end(), "abc") != v.end()) { // Element in vector. } To be able to use std::find : include <algorithm> . If your container only contains