https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67932
--- Comment #2 from R Copley <rcopley at gmail dot com> --- Thanks Jonathan. It's clear enough from what I wrote that: (1) The same kind of incorrect output is produced by (a) including <cstdio> and using std::printf, and (b) using iostreams and std::hexfloat; (2) The correct output is produced by including <stdio.h> and using ::printf. I think (but I am by no means certain!) that (by (2)) my C library works, and (by (1)) there is a problem with GCC's standard library implementation.
