stdvector

I'm trying to load an object and use VBO and glDrawArrays() to render it. The problem is that a simple float pointer like float f[]={...} does not work in my case, because I passed the limit of values that this pointer can store. So my solution was to use a vector. And it's not working... Here is my code: unsigned int vbo; vector<float*> vert; ... vert.push_back(new float(i*size)); vert.push_back(new float(height*h)); vert.push_back(new float(j*size)); ... glGenBuffers(1, &vbo); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, sizeof(vert), &vert, GL_STATIC_DRAW); glBindBuffer

Lets say I have 30000 objects in my vector/list. Which I add one by one. I need them sorted. Is it faster to sort all at once (like std::sort), or keep vector/list sorted while I add object one by one? vector/list WILL NOT be modified later. When you are keeping your vector list sorted while inserting elements one by one , you are basically performing an insertion sort, that theoretically runs O(n^2) in worst case. The average case is also quadratic, which makes insertion sort impractical for sorting large arrays. With your input of ~30000 , it will be better to take all inputs and then sort

edit: I am specifically comparing std::vector 's linear search operations to the std::map binary search operations because that is what Herb's claim seemed to relate to. I know that using a binary search will move the performance from O(N) to O(log N) but that would not be testing Herb's claim Bjarne Stroustrup and Herb Sutter have both recently talked about how awesome std::vector is in situations one would expect std::list to be used, owing to the cost of cache misses during linked list traversal. (see http://channel9.msdn.com/Events/Build/2014/2-661 at the 48 minute mark) Herb made a

In many languages, there are generators that help to initialize collections. In C++, if one wants to initialize a vector uniformly, one can write: std::vector<int> vec(10, 42); // get 10 elements, each equals 42 What if one wants to generate different values on the fly? For example, initialize it with 10 random values, or consecutive numbers from 0 to 9? This syntax would be convenient, but it does not work in C++11: int cnt = 0; std::vector<int> vec(10, [&cnt]()->int { return cnt++;}); Is there a nice way to initialize a collection by iterative function calls? I currently use this ugly

I have to read some .mat data files from c++, I read through the documentation, but I would like to know how to handle the data in a clean and elegant way, e.g. using std:vector(modest .mat file size(10M~1G), but memory issues should be taken seriously) My function is sth like: #include <stdio.h> #include "mat.h" #include <vector> int matread(const char *file, const vector<double>& pdata_v) { MATFile *pmat; pmat=matOpen("data.mat","r"); if (pmat == NULL) { printf("Error opening file %s\n", file); return(1); } mxArray *pdata = matGetVariable(pmat, "LocalDouble"); // pdata -> pdata_v mxDestroy

I can't seem to think of a reliable way (that also compacts memory) to remove the first N elements from a std::vector . How would one go about doing that? Mark Ransom Since you mention that you want to compact memory, it would be best to copy everything to a new vector and use the swap idiom. std::vector<decltype(myvector)::value_type>(myvector.begin()+N, myvector.end()).swap(myvector); Use the .erase() method: // Remove the first N elements, and shift everything else down by N indices myvec.erase(myvec.begin(), myvec.begin() + N); This will require copying all of the elements from indices N+1