The following code example is taken from the book
C++23 - The Complete Guide
by Nicolai M. Josuttis,
Leanpub, 2026
The code is licensed under a
Creative Commons Attribution 4.0 International License.
// raw code
#include <print>
#include <array>
#include <exception>
#include <string>
template<typename T, int SZ1, int SZ2>
requires (SZ1 > 0 && SZ2 > 0)
class Array2D
{
std::array<T, SZ1 * SZ2> data = {};
public:
Array2D() = default;
Array2D(auto... args)
: data{args...} {
}
// read access for two dimensions:
const auto& @\TB{operator[]}@ (int x, int y) const {
if (x < 0 || x >= SZ1) {
throw std::out_of_range{"invalid row " + std::to_string(x)};
}
if (y < 0 || y >= SZ2) {
throw std::out_of_range{"invalid column " + std::to_string(x)};
}
return data[x * SZ2 + y];
}
// write access for two dimensions:
auto& @\TB{operator[]}@ (int x, int y) {
if (x < 0 || x >= SZ1) {
throw std::out_of_range{"invalid row " + std::to_string(x)};
}
if (y < 0 || y >= SZ2) {
throw std::out_of_range{"invalid column " + std::to_string(x)};
}
return data[x * SZ2 + y];
}
void print() const {
std::println("{}", data);
}
};