Allen Wayne Best <gcc@xxxxxxxxxxxxxxxxxx> writes: > g++ -g -O2 -o motor motor.o sensor.o > motor.o(.text+0x7cd): In function `main': > /home/best/engine-project/control-module/project/src/motor.cpp:67: undefined > reference to `Measure::operator<<(std::basic_ostream<char, > std::char_traits<char> >&, Measure::Sensor const&)' > collect2: ld returned 1 exit status > > any suggestions are greatly appreciated! tia! I suggest that you put together a complete test case in a single file, rather than using piece-meal bits. You haven't provided enough information to show what has gone wrong. In particular, the error message refers to Measure, which was not in your sample code at all, but may be an important part of the problem. Ian
