lst-0104-book.cpp
// https://godbolt.org/z/Yd4sser5j
#include <complex>
// raw form
int operator"" _dual(const char*);
int answer = 101010_dual; // decimal 42
// preprocessed form
std::complex<long double> operator"" _i(long double d) {
return std::complex<long double>(0, d);
}
auto val = 3.14_i; // val = std::complex<long double>(0, 3.14)