I am trying to build a small program and I have my own library libfoo. I have a camera class that is calling a static function from my Vector3 class (i.e. crossProduct). My camera class and Vector3 class compile ok and are built into libfoo. However when I am linking like so:
g++ -g -O2 -o test1 main.o -lfoo
I get this:
libfoo.so: undefined reference to foo::Vector3::dotProduct(foo::Vector3 const&, foo::Vector3 const&)
Now the function in Vector3.h is:
static Vector3 crossProduct(const Vector3 &v1, const Vector3 &v2); and is within the
class definition… and it is defined in Vector3.cpp.
The program was fine until i called this static function inside Camera.cpp. In order to fix the problem I have to change the code in Vector3.cpp from what is in the header file to:
Vector3 Vector3::crossProduct(const Vector3 &v1, const Vector3 &v2) and it compiles, links, and runs OK.
The Vector3 class was written by someone else for a windows compiler, but I have moved it to Linux. Is this a g++ thing? Or bad code?
It sounds like your vector3.cpp file originally had the following:
which you had to change to:
The former is just defining a standalone function called crossProduct, whereas the latter is defining a member function of Vector3 called crossProduct. The latter is correct and what i'm guessing to be the original code was incorrect.