c++ - How to get the coefficient from a std::decimal? -


background

i want write is_even( decimal::decimal64 d ) function returns true if least-significant digit even.

unfortunately, can't seem find methods extract coefficient decimal64.

code

#include <iostream> #include <decimal/decimal>  using namespace std;  static bool is_even( decimal::decimal64 d ) {     return true;  // fix - want to: return coefficient(d)%2==0; } int main() {     auto d1 = decimal::make_decimal64( 60817ull, -4 );   // not     auto d2 = decimal::make_decimal64( 60816ull, -4 );   //      cout << decimal64_to_float( d1 ) << " " << is_even( d1 ) << endl;      cout << decimal64_to_float( d2 ) << " " << is_even( d2 ) << endl;      return 0; }

it's little odd there's no provided function recover coefficient of decimal; can multiply 10 raised negative exponent:

bool is_even(decimal::decimal64 d) {     auto q = quantexpd64(d);     auto coeff = static_cast<long long>(d * decimal::make_decimal64(1, -q));     return coeff % 2 == 0; }  assert(!is_even(decimal::make_decimal64(60817ull, -4))); assert(!is_even(decimal::make_decimal64(60816ull, -4)));

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