I'm nowhere close to being qualifed to write
something
about
CXX/CFLAGS. Somebody else (not you) should
provide a
paragraph
addressing those variables.
Read the
documentation for gcc and make. They control
how a program is compiled and can make a huge
difference. The developer should know what the options
do before they are set. Variables like CFLAGS and
CXXFLAGS are often set or modified in a Makefile.
For qt based apps, it would also be helpful to read through
the qmake manual as that generally is used, via a .pro file,
to generate the Makefile for an application or library.
I have no problem with learning, but an RTFM response rather than helping is lame. :)