hi, I am using openGL and am currently passing it a vertex array. The problem is that I have to create many vertices, and add them in between one another (for order). This means that using a regular array is pretty annoying/inefficient. I want to use a data structure from STL so that I can efficiently (and easily) put new vertices at a...
Okay I have a bit of a problem which i'm struggling to solve. Basically I have an abstract functor class that overloads operator() and derived objects that implement it. I have a function (part of another class) that tries to take an Array of these functor classes and tries to pass a pointer to a member function to the std algorithm fo...
#include <vector> #include <functional> #include <algorithm> using namespace std; struct Foo { int i; double d; Foo(int i, double d) : i(i), d(d) {} int getI() const { return i; } }; int main() { vector<Foo> v; v.push_back(Foo(1, 2.0)); v.push_back(Foo(5, 3.0)); vector<int> is; ...
I have a vector containing few non-adjacent duplicates. As a simple example, consider: 2 1 6 1 4 6 2 1 1 I am trying to make this vector unique by removing the non-adjacent duplicates and maintaining the order of elements. Result would be: 2 1 6 4 The solutions I tried are: Inserting into a std::set but the problem with this a...
I have some complicated C++ code but the problem narrows down to doing a push_back on a list of structures: list<cache_page> cachedPages; void f() { cache_page cpage(a,b); cachedPages.push_back(cpage); } I have commented all the data members of the struct cache_page and still the error persists. If I comment the push_back lin...
For instance why does most members in STL implementation have M or _ or __ prefix? Why there is so much boilerplate code ? What features C++ is lacking that would allow make vector (for instance) implementation clear and more concise? ...
It is used in /usr/include/c++/4.3/stl_list.h on my system (current Ubuntu). ...
I was doing a quick performance test on a block of code void ConvertToFloat( const std::vector< short >& audioBlock, std::vector< float >& out ) { const float rcpShortMax = 1.0f / (float)SHRT_MAX; out.resize( audioBlock.size() ); for( size_t i = 0; i < audioBlock.size(); i++ ) { out[i] = (float...
I have a simple class like this: class A { public: void f(const int& n) { std::cout<<"A::f()" << n <<"\n"; } }; and I am trying to use it like this: std::vector<A> vec; A a; vec.push_back(a); std::for_each(vec.begin(), vec.end(), std::bind2nd(std::mem_fun_ref(&A::f), 9)); But when I compile the code I get the follo...
Is it possible to transfer ownership of a vector contents from one vector to another? vector<T> v1; // fill v1 vector<T> v2 = OvertakeContents(v1); // now v1 would be empty and v2 would have all the contents of v1 It is possible for lists with splice function. This should be possible in constant time for whole vector as well. If it...
Having read the claim multiple times in articles - I want to add this question to Stackoverflow, and ask the community - is the following code portable? template<template<typename T, typename Alloc> class C> void f() { /* some code goes here ... */ } int main() { f<std::vector>(); } Is the implementation that supplies std::vector...
Does anyone know an efficient way to right circular-shift a matrix? Btw, the matrix is binary but a method to solve a non-binary matrix is also fine. Right now, I'm thinking of implementing a circular array for the rows of my matrix and updating each row whenever a shift operation is required. Another method, I was considering was impl...
I have a sequence, e.g std::vector< Foo > someVariable; and I want a loop which iterates through everything in it. I could do this: for (int i=0;i<someVariable.size();i++) { blah(someVariable[i].x,someVariable[i].y); woop(someVariable[i].z); } or I could do this: for (std::vector< Foo >::iterator i=someVariable.begin(); i...
I have to read a lot of data into: vector<char> A 3rd party library reads this data in many turns. In each turn it calls my callback function whose signature is like this: CallbackFun ( int CBMsgFileItemID, unsigned long CBtag, void* CBuserInfo, int CBdataSize, void* CBdataBuffe...
Consider the piece of code: class Foo { // ... std::vector<Bar> bars; }; Should I expose the whole container, or should I expose typedef'd iterator class and write adaptor methods (begin(), end(), size(), and whatever I need)? If the answer is it depends, how should one make a decision? ...
How do I require and check that an argument is a certain concept in C++? For example, the random_shuffle function in the algorithm header requires that its arguments are RandomAccessIterators: template<typename _RandomAccessIterator> inline void random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last) {...
Hi, I have 2 std::string. I just want to, given the input string: capitalize every letter assign the capitalized letter to the output string. How come this works: std::string s="hello"; std::string out; std::transform(s.begin(), s.end(), std::back_inserter(out), std::toupper); but this doesn't (results in a program crash)?...
Or ostringstream? istringstream a("asd"); istringstream b = a; // This does not work. I guess memcpy won't work either. ...
I need to create a pool of objects to eliminate dynamic allocations. Is it efficient to use std::stack to contain pointers of allocated objects? I suspect every time I push the released object back to stack a new stack element will be dynamically allocated. Am I right? Should I use std::vector to make sure nothing new is allocated? Tha...
I have to do calculation on array of 1,2,3...9 dimensional vectors, and the number of those vectors varies significantly (say from 100 to up to couple of millions). Of course, it would be great if the data container can be easily decomposed to enable parallel algorithms. I came across blitz++(almost impossible to compile for me), but a...