Is std::vector memory freed upon a clear?

Suppose I have a std::vector of structs. What happens to the memory if the vector is clear()’d? std::vector<myStruct> vecs; vecs.resize(10000); vecs.clear(); Will the memory be freed, or still attached to the vecs variable as a reusable buffer? Answer The memory remains attached to the vector. That isn’t just likely either. It’s required. In particular, if … Read more

What is the most efficient way to append one std::vector to the end of another?

Let v1 be the target vector, v2 needs to be appended to the back of it. I’m now doing: v1.reserve(v1.size() + v2.size()); copy(v2.begin(), v2.end(), back_inserter(v1)); Is this the most efficient way? Or can it maybe be done just via copying a chunk of memory? Thanks! Answer After a lot of arguing (and a reasonable comment … Read more

How can i add padding vector file in android

How can i add paddingleft,Right,Top and bottom veriable in my vector file. I changed android:viewportWidth and android:viewportHeight But Nothing change My Vector <vector xmlns:android=”” android:width=”31.416dp” android:height=”31.416dp” android:viewportWidth=”31.416″ android:viewportHeight=”31.416″> <path android:fillColor=”#fff” android:pathData=”M28.755,6.968l-0.47,0.149L25.782,7.34l-0.707,1.129l-0.513-0.163L22.57,6.51l-0.289-0.934L21.894,4.58l-1.252-1.123 l-1.477-0.289l-0.034,0.676l1.447,1.412l0.708,0.834L20.49,6.506l-0.648-0.191L18.871,5.91l0.033-0.783l-1.274-0.524l-0.423,1.841 l-1.284,0.291l0.127,1.027l1.673,0.322l0.289-1.641l1.381,0.204l0.642,0.376h1.03l0.705,1.412l1.869,1.896l-0.137,0.737 l-1.507-0.192l-2.604,1.315l-1.875,2.249l-0.244,0.996h-0.673l-1.254-0.578l-1.218,0.578l0.303,1.285l0.53-0.611l0.932-0.029 l-0.065,1.154l0.772,0.226l0.771,0.866l1.259-0.354l1.438,0.227l1.67,0.449l0.834,0.098l1.414,1.605l2.729,1.605l-1.765,3.372 l-1.863,0.866l-0.707,1.927l-2.696,1.8l-0.287,1.038c6.892-1.66,12.019-7.851,12.019-15.253 C31.413,12.474,30.433,9.465,28.755,6.968z” /> <path android:fillColor=”#fff” android:pathData=”M17.515,23.917l-1.144-2.121l1.05-2.188l-1.05-0.314l-1.179-1.184l-2.612-0.586l-0.867-1.814v1.077h-0.382l-2.251-3.052 v-2.507L7.43,8.545L4.81,9.012H3.045L2.157,8.43L3.29,7.532L2.16,7.793c-1.362,2.326-2.156,5.025-2.156,7.916 c0,8.673,7.031,15.707,15.705,15.707c0.668,0,1.323-0.059,1.971-0.137l-0.164-1.903c0,0,0.721-2.826,0.721-2.922 C18.236,26.357,17.515,23.917,17.515,23.917z” /> <path android:fillColor=”#fff” android:pathData=”M5.84,5.065l2.79-0.389l1.286-0.705l1.447,0.417l2.312-0.128l0.792-1.245l1.155,0.19l2.805-0.263L19.2,2.09l1.09-0.728 l1.542,0.232l0.562-0.085C20.363,0.553,18.103,0,15.708,0C10.833,0,6.474,2.222,3.596,5.711h0.008L5.84,5.065z M16.372,1.562 l1.604-0.883l1.03,0.595l-1.491,1.135l-1.424,0.143l-0.641-0.416L16.372,1.562z M11.621,1.691l0.708,0.295l0.927-0.295 l0.505,0.875l-2.14,0.562l-1.029-0.602C10.591,2.526,11.598,1.878,11.621,1.691z” /> </vector> … Read more

How do I sort a std::vector by the values of a different std::vector?

I have several std::vector, all of the same length. I want to sort one of these vectors, and apply the same transformation to all of the other vectors. Is there a neat way of doing this? (preferably using the STL or Boost)? Some of the vectors hold ints and some of them std::strings. Pseudo code: … Read more

Vectors in Arduino

I am making a vector of “waypoints” on the Arduino. Each waypoint is an object. The Arduino will obviously need to store multiple waypoints for waypoint navigation. But instead of storing these waypoints in a standard preprogrammed array, the user will need to be able to add, remove waypoints and move them around. Unfortunately the … Read more

how do you insert the value in a sorted vector?

ALL, This question is a continuation of this one. I think that STL misses this functionality, but it just my IMHO. Now, to the question. Consider following code: class Foo { public: Foo(); int paramA, paramB; std::string name; }; struct Sorter { bool operator()(const Foo &foo1, const Foo &foo2) const { switch( paramSorter ) { … Read more

How do I sum a vector using fold?

This Rust tutorial explains the fold() mechanism well, and this example code: let sum = (1..4).fold(0, |sum, x| sum + x); works as expected. I’d like to run it on a vector, so based on that example, first I wrote this: let sum: u32 = vec![1,2,3,4,5,6].iter().fold(0, |sum, val| sum += val); which threw an error: … Read more

Convert Mat to Array/Vector in OpenCV

I am novice in OpenCV. Recently, I have troubles finding OpenCV functions to convert from Mat to Array. I researched with .ptr and .at methods available in OpenCV APIs, but I could not get proper data. I would like to have direct conversion from Mat to Array(if available, if not to Vector). I need OpenCV … Read more