std-pair

I didn't find anyone answering this, is there any difference between the following : v.push_back({x, y}); and : v.push_back(make_pair(x, y)); Assuming that v was declared this way : vector<pair<int,int> > v; I tried this in an online compiler, and as far as I can see the optimized assembly for make_pair is identical to {} syntax. https://godbolt.org/z/P7Ugkt I think you might have accepted that answer a little too quickly. The commonly accepted way to do this is like this: vec.emplace_back (x, y); And if you look at Godbolt, you can see that this inlines everything (which may or may not be

So I have a smart iterator that emulates a map const_iterator, and it needs to build the return type internally. Obviously, I'd like to store a pair<Key, Value> in my iterator class (since I need to modify it), but at the same time I'd like the dereference functions to present a pair<const Key, Value> (actually it would be a const pair<const Key, Value>& and const pair<const Key, Value>* respectively). The only solution I've come up with so far is to dynamically allocate a new pair every time change the value that my iterator class points to changes. Needless to say, this is not a good

A common design problem I run into, is that I bundle two variables together and then lose the ability to reference them in a meaningful way. std::pair<int,int> cords; cord.first = 0; //is .first the x or y coordinate? cord.second = 0; //is .second the x or y coordinate? I've considered writing basic structs instead, but then I lose a lot of the benefits that come along with std::pair : make_pair non-member overloaded operators swap get etc. Is there a way to rename or provide an alternative identifier for the first and second data members? I was hoping to leverage all of the the functions that

Sorry for a little bit beginner question. There are vector and vector of pairs typedef std::vector <int> TItems; typedef std::vector < std::pair <int, int> > TPairs; Is there any way to transform all first items in pair to another vector in one step int main () { TItems items; TPairs pairs; pairs.push_back (std::make_pair(1,3)); pairs.push_back (std::make_pair(5,7)); std::transform( items.begin(), items.end(), items.begin(), comp ( &pairs ) ); return 0; } How to design a functor? class comp { private: TPairs *pairs; public: comp ( TPairs *pairs_ ) : pairs ( pairs_) { } unsigned int operator ()