#include <array>

#include <iostream>

void test_two_dim_array() {

int multi_array_native[3][4];

std::array<std::array<int, 3>, 4> multi_array;

///< 但其实它俩不相同，应该是

std::array<std::array<int, 4>, 3> multi_arrays;

}

template <typename T, size_t R, size_t C>

using TwoDimMatrix = std::array<std::array<T, C>, R>;

void test_two_dim_matrix() {

constexpr size_t row = 2;

constexpr size_t col = 3;

TwoDimMatrix<int, row, col> mat;

int k = 0;

for (int i = 0; i < row; ++i) {

for (int j = 0; j < col; ++j) {

mat[i][j] = ++k;

}

}

for (int i = 0; i < row; ++i) {

for (int j = 0; j < col; ++j) {

std::cout << mat[i][j] << " ";

}

}

}

///< 利用模板元编程

template <typename T, size_t R, size_t... C>

struct Matrix {

using Col = typename Matrix<T, C...>::type;

using type = std::array<Col, R>;

};

template <typename T, size_t R>

struct Matrix<T, R> {

using type = std::array<T, R>;

};

void test_multi_array() {

constexpr size_t a = 2;

constexpr size_t b = 3;

constexpr size_t c = 4;

constexpr size_t d = 5;

Matrix<int, a, b, c, d>::type mat;

int u = 0;

for (int i = 0; i < a; ++i) {

for (int j = 0; j < b; ++j) {

for (int k = 0; k < c; ++k) {

for (int m = 0; m < d; ++m) {

mat[i][j][k][m] = ++u;

}

}

}

}

for (int i = 0; i < a; ++i) {

for (int j = 0; j < b; ++j) {

for (int k = 0; k < c; ++k) {

for (int m = 0; m < d; ++m) {

std::cout << mat[i][j][k][m] << " ";

}

}

}

}

}

int main() {

test_two_dim_matrix();

std::cout << "\n";

test_multi_array();

}