c++ class why need main?

Question

Hello I\'m writing a little project in c++ where I would like to have some classes that does some work, I wrote the interfaces and the implementation of the classes.

The

Answer 1

First, this is wrong: animal dog = new animal();

You either need

animal * dog = new animal();
cout << dog->method1(42);
delete animal;

or preferably just

animal dog;

Second, you need to link together the object files produced by compiling your two source .cpp files.

gcc -o animal animal.cpp app.cpp 

should do the trick, if you're using gcc.