Arrays / Array size type safe at compile time / Essential C++
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#include <cstddef> // size_t, ptrdiff_t
using Size = ptrdiff_t;
template< class Item, size_t n >
constexpr auto n_items( Item (&)[n] ) noexcept
-> Size
{ return n; }
#include <iostream>
using namespace std;
auto main()
-> int
{
int const a[] = {3, 1, 4, 1, 5, 9, 2, 6, 5, 4};
Size const n = n_items( a );
int b[n] = {}; // An array of the same size as a.
(void) b;
cout << "Size = " << n << "\n";
}
Cpp
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