I want to use initializer lists for my vectors and arrays. Ultimately, I would like to initialize an array of vectors of some class A, but I do not get there while getting weird compiler errors. Here is some code: #include <vector> #include <array> class A { public: A(int x_, int y_): x(x_), y(y_) {} ..
Category : aggregate-initialization
With std::array you can do std::array<int,3> v = {1,2,3}; But I want to provide a wrapper template <typename T, int n> circular_array { auto operator[](size_t i){ return m_data[i%n]; } // TODO forward all other methods directly except “at“ which we don’t need private: std::array<t,n> m_data; } but I lose the aggregate initialization that I had ..
I’ve run into an interesting warning (with GCC and clang -Wnarrowing at least, haven’t tested other compilers), when aggregate initialising a struct using a ternary operator expression (see below code). I don’t understand why the type of the expression is apparently considered int in the aggregate initialisation case, but is silently coerced to be a ..
I want to make my own struct for a 3×3 Matrix. I want to allow construction via components/elements or by "rows". So either you provide a std::array<float, 9> or a std::array<std::array<float, 3>, 3> However when defining the struct like this with the following constructors: struct Matrix3x3 { Matrix3x3(std::array<float, 9> components) { } Matrix3x3(std::array<std::array<float, 3>, 3> ..
I want to make my own struct for a 3×3 Matrix. I want to allow construction via components/elements or by "rows". So either you provide a std::array<float, 9> or a std::array<std::array<float, 3>, 3> However when defining the struct like this with the following constructors: struct Matrix3x3 { Matrix3x3(std::array<float, 9> components) { } Matrix3x3(std::array<std::array<float, 3>, 3> ..
I have a problem compiling this simple aggregate named initialization with g++ struct A { int a; }; struct B { int b; }; struct C { A a; B b; }; void fun() { A a{0}; B b {12} ; // g++ is OK with this C c{ .a=a , .b=b }; // g++ ..
I always thought that aggregate initialization was to save coders from writing custom constructors. However, this seems to have "sneaked in" a "security by-pass" for private constructors. Say I have class A which I only want to be created by class B. struct A { friend class B; const int i, k; private: A () ..
See this example: https://godbolt.org/z/5PqYWP How come this array of pairs can’t be initialized in the same way as a vector of pairs? #include <vector> #include <array> int main() { std::vector<std::pair<int,int>> v{{1,2},{3,4},{5,6}}; // succeeds std::array <std::pair<int,int>, 3> a{{1,2},{3,4},{5,6}}; // fails to compile } Source: Windows Que..
I want to make it possible to pass brace-enclosed initializer list to my constructor of my class which represents a matrix of fixed dimension. This is the code what I have: #include <cstddef> #include <array> template <typename T, size_t N, size_t M> using array2d = std::array<std::array<T, N>, M>; template <typename T, size_t N, size_t M> ..
I was reading on template deduction then tried to create one. as follows:- #include <iostream> #include <array> using namespace std; template<int i,typename A,typename… B> struct deducted{ }; //Deduction guide template<typename A,typename… B> deducted(A a,B… b)->deducted<0,A,B…>; // int main(){ deducted a={"","",""}; deducted b={0,0,0}; array c={0,0,0}; } what supprises me is the test fails with error: too ..
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