what is __printf_fp() and when is it called?

Question

After using callgrind to profile my code, I see that __printf_fp() is the function with more value in the self column. What is this function and when is it called?

Thank you!

Answer 1

__printf_pf() belongs to the libstdc++ library. It is mainly called by any printf related function (ostream, ofstream, etc). However, when it is called depends on the compiler and compiler's version as pointed out here: C++ output stream floating point call chain