Defining multi-dimensional array using the T[][][]
syntax is easy. However, this creates a raw array type which doesn't fit nicely into modern C++. That's why we have std::array
since C++11. But the syntax to define a multi-dimensional array using std::array
is quite messy. For example, to define a three-dimensional int
array, you would have to write std::array<std::array<std::array<int, 5>, 5>, 5>
. The syntax doesn't scale at all. I'm asking for a fix for this issue. Maybe, this issue cannot be fixed using existing utility provided by C++. In that case, I'm happy with a custom tool developed to ease the syntax.
Found a solution myself:
template <typename T, std::size_t n, std::size_t... ns>
struct multi_array {
using type = std::array<typename multi_array<T, ns...>::type, n>;
};
template <typename T, std::size_t n>
struct multi_array<T, n> {
using type = std::array<T, n>;
};
template <typename T, std::size_t... ns>
using multi_array_t = typename multi_array<T, ns...>::type;
Wondering whether the implementation can be further simplified.
Refer to Multi-dimensional arrays in C++11
template <class T, std::size_t I, std::size_t... J>
struct MultiDimArray
{
using Nested = typename MultiDimArray<T, J...>::type;
// typedef typename MultiDimArray<T, J...>::type Nested;
using type = std::array<Nested, I>;
// typedef std::array<Nested, I> type;
};
template <class T, std::size_t I>
struct MultiDimArray<T, I>
{
using type = std::array<T, I>;
// typedef std::array<T, I> type;
};
MultiDimArray<float, 3, 4, 5, 6, 7>::type floats;
MultiDimArray
is a pair of meta-functions to compute nested type for multi-dimensional std::array
. The most general MultiDimArray
is a variadic template of unsigned integers to pass an arbitrary number of dimensions. The terminating MultiDimArray
specialization defines the simplest case of single dimensional std::array
.
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