Very surprising perfs of fprintf vs std::ofstream (fprintf is very slow)

Question

I was running some benchmarks to find the most efficient way to write a huge array to a file in C++ (more than 1Go in ASCII).

So I compared std::ofstream with fprintf (s

Answer 1

fprintf("%d" requires runtime parsing of the format string, once per integer. ostream& operator<<(ostream&, int) is resolved by the compiler, once per compilation.