As long as the managed code does not resize the vector, you can access the buffer and pass it as a pointer with vector.data() (for C++0x) or &vector[0]. This results in a zero-copy system. Example C++ API: #define EXPORT extern “C” __declspec(dllexport) typedef intptr_t ItemListHandle; EXPORT bool GenerateItems(ItemListHandle* hItems, double** itemsFound, int* itemCount) { auto … Read more
Like this.. Containers in the standard usually take an allocator. Using c++11’s allocator traits, it is very easy to create an allocator as you don’t have to have all the members in the allocator. However if using an older version of C++, you will need to implement each member and do the rebinding as well! … Read more
Maybe this clause from 8.5.4.5 explains it (my emphasis): An object of type std::initializer_list is constructed from an initializer list as if the implementation allocated an array of N elements of type E, where N is the number of elements in the initializer list. Each element of that array is copy-initialized with the corresponding element … Read more
Your loop is wrong: for (int i=0; i=((Main.size())-1); i++) { Try this: for (int i=0; i < Main.size(); i++) { Also, a more idiomatic way of reading numbers into a vector and writing them to stdout is something along these lines: #include <iostream> #include <iterator> #include <fstream> #include <vector> #include <algorithm> // for std::copy int … Read more
Maybe someone is searching for an answer, like me for two days now: // Draw a path and hide it: var root = paper.path(‘M0 50L30 50Q100 100 50 50’).hide(); var length = root.getTotalLength(); // Setup your animation (in my case jQuery): element.animate({ ‘to’: 1 }, { duration: 500, step: function(pos, fx) { var offset = … Read more
vector<vector<int> > a; If you want to define the rows and columns, vector<vector<int> > a{{11, 2, 4}, {4, 5, 6}, {10, 8, -12}};
vector requires that the values are movable, in order to maintain a contiguous array of values as it grows. You could create a vector containing mutexes, but you couldn’t do anything that might need to resize it. Other containers don’t have that requirement; either deque or [forward_]list should work, as long as you construct the … Read more
std::remove_if comes to the rescue! 99 would be replaced by UnaryPredicate that would filter your delays, which I am going to use a lambda function for. And here’s the example: v.erase(std::remove_if( v.begin(), v.end(), [](const int& x) { return x > 10; // put your condition here }), v.end());
There is no need to completely sort the vector: std::nth_element can do enough work to put the median in the correct position. See my answer to this question for an example. Of course, that doesn’t help if your teacher forbids using the right tool for the job.
You cannot do this: vector<string> name(5); //error in these 2 lines vector<int> val(5,0); in a class outside of a method. You can initialize the data members at the point of declaration, but not with () brackets: class Foo { vector<string> name = vector<string>(5); vector<int> val{vector<int>(5,0)}; }; Before C++11, you need to declare them first, then … Read more