templates - C++ binary constant/literal

Question

I'm using a well known template to allow binary constants

template< unsigned long long N >
struct binary
{
  enum { value = (N % 10) + 2 * binary< N / 10 > :: value } ;
};

template<>
struct binary< 0 >
{
  enum { value = 0 } ;
};

So you can do something like binary<101011011>::value. Unfortunately this has a limit of 20 digits for a unsigned long long.

Does anyone have a better solution?

Answer 1

Does this work if you have a leading zero on your binary value? A leading zero makes the constant octal rather than decimal.

Which leads to a way to squeeze a couple more digits out of this solution - always start your binary constant with a zero! Then replace the 10's in your template with 8's.