c++20/chapter-1.cpp

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// ===-- chapter-1/c++20/chapter-1.cpp -------------------- -*- C++ -*- --=== //
#include <cstdint>
#include <stdio.h>
 
 
namespace chapter1 {
 
inline namespace cpp20 {
 
constexpr uint32_t binary_func(uint64_t const N)
{
    return (N == 0) ? 0 : (N % 10) + (2 * binary_func(N/10));
}
 
consteval uint32_t binary(uint64_t const N)
{
    return binary_func(N);
}
 
} // inline namespace cpp20
} // namespace chapter1
 
 
namespace {
using namespace chapter1;
 
constexpr struct { uint32_t expected; uint32_t got; } run[] = {
    {.expected = 1, .got = binary(1)},
    {.expected = 3, .got = binary(11)},
    {.expected = 5, .got = binary(101)},
    {.expected = 7, .got = binary(111)},
    {.expected = 9, .got = binary(1001)},
};
 
} // namespace <anon>
 
int main()
{
    using namespace chapter1;
 
    for (auto const& vals : run) {
        printf("Should be %u: %u\n", vals.expected, vals.got);
    }
    return 0;
}