C++ std::array Initializing an std::array
Example
Initializing std::array<T, N>, where T is a scalar type and N is the number of elements of type T
If T is a scalar type, std::array can be initialized in the following ways:
// 1) Using aggregate-initialization
std::array<int, 3> a{ 0, 1, 2 };
// or equivalently
std::array<int, 3> a = { 0, 1, 2 };
// 2) Using the copy constructor
std::array<int, 3> a{ 0, 1, 2 };
std::array<int, 3> a2(a);
// or equivalently
std::array<int, 3> a2 = a;
// 3) Using the move constructor
std::array<int, 3> a = std::array<int, 3>{ 0, 1, 2 };
Initializing std::array<T, N>, where T is a non-scalar type and N is the
number of elements of type T
If T is a non-scalar type std::array can be initialized in the following ways:
struct A { int values[3]; }; // An aggregate type
// 1) Using aggregate initialization with brace elision
// It works only if T is an aggregate type!
std::array<A, 2> a{ 0, 1, 2, 3, 4, 5 };
// or equivalently
std::array<A, 2> a = { 0, 1, 2, 3, 4, 5 };
// 2) Using aggregate initialization with brace initialization of sub-elements
std::array<A, 2> a{ A{ 0, 1, 2 }, A{ 3, 4, 5 } };
// or equivalently
std::array<A, 2> a = { A{ 0, 1, 2 }, A{ 3, 4, 5 } };
// 3)
std::array<A, 2> a{{ { 0, 1, 2 }, { 3, 4, 5 } }};
// or equivalently
std::array<A, 2> a = {{ { 0, 1, 2 }, { 3, 4, 5 } }};
// 4) Using the copy constructor
std::array<A, 2> a{ 1, 2, 3 };
std::array<A, 2> a2(a);
// or equivalently
std::array<A, 2> a2 = a;
// 5) Using the move constructor
std::array<A, 2> a = std::array<A, 2>{ 0, 1, 2, 3, 4, 5 };
