prog.cpp: In member function 'bool CCompare::operator()(C&, C&)':
prog.cpp:7: error: 'double C::a' is protected
prog.cpp:19: error: within this context
prog.cpp:7: error: 'double C::a' is protected
prog.cpp:19: error: within this context
prog.cpp:7: error: 'double C::b' is protected
prog.cpp:19: error: within this context
prog.cpp:7: error: 'double C::b' is protected
prog.cpp:19: error: within this context
prog.cpp:7: error: 'double C::a' is protected
prog.cpp:19: error: within this context
prog.cpp:7: error: 'double C::a' is protected
prog.cpp:19: error: within this context
prog.cpp:7: error: 'double C::b' is protected
prog.cpp:19: error: within this context
prog.cpp:7: error: 'double C::b' is protected
prog.cpp:19: error: within this context