I don't really understand your question. Can you please post a sample code?
I tried to created a sample code for what I understand from your question.
class InterfaceSampleCode
{
virtual void PureVirtualMethod() = 0;
};
If you implement the above method is will be implemented in the source file as expected. Is this what you mean? Do you want it to be in the header? If yes, can you please explain why? If I misunderstood you, can you please post a sample code?