I want to define a 2D array of structures in a class in C++, how should I do it, here is an example approach for a struct tt
class swtlvn{ private: int a,b; tt yum[a][b]; }; Can this be done in some way? This AoS will be used by all the member functions of the class/ultimatey defined object so it cant be defined inside a member function. Having it defined externally is going to be a hassle so no can do.
EDIT:
struct tt{ int a,b,c; tt(){} tt(int aa,int bb,int cc){a = aa; b = bb; c = cc;} }; Without knowing more, I would say you should use something similar to:
class Foo { public: Foo(int _a, int _b) : a(_a), b(_b) { yum.resize(a); for (size_t i = 0; i < a; i++) { yum[i].resize(b); } } typedef std::vector<std::vector<tt> > TtVector2D; TtVector2D yum; }; Can this be done in some way
If tt has proper copy semantics, then one solution is to use std::vector<std::vector<tt>>:
#include <vector> struct tt { int a,b,c; tt(int aa=0, int bb=0, int cc=0) : a(aa), b(bb), c(cc) {} }; class swtlvn { private: int a,b; std::vector<std::vector<tt>> yum; public: swtlvn(int a_, int b_) : a(a_), b(b_), yum(a_, std::vector<tt>(b_)) {} }; int main() { swtlvn f(10, 20); } // for example Also, once you have a std::vector, I don't recommend using extraneous member variables such as a and b to denote the size. A vector knows its own size by utilizing the std::vector::size() member function.
aandbgoing to be know at compile time or run time? If run time I suggest you use astd::vector.tt. It may be able to be used invector, but has to have proper copy semantics first.std::arrayoverstd::vectorif efficiency is a concern. stackoverflow.com/questions/4424579/…