How to print __int128 in g++?

Question

I am using the GCC built-in type __int128 for a few things in my C++ program, nothing really significant, at least not enough to justify to use BigInt library o

Answer 1

A deceptively simple approach

std::ostream& operator<<(std::ostream& os, __int128 x){
    if(x<0) return os << "-" << -x;
    if(x<10) return  os << (char)(x+'0');
    return os << x/10 << (char)(x%10+'0');
}

See my other comment for a failed attempt at a more performant implementation.