do I need a return after throwing exception (c++ and c#)

I have a function that generate an exception. For example the following code:

void test()
{
    ifstream test("c:/afile.txt");
    if(!test)
    { 
         throw exception("can not open file");
    }
    // other section of code that reads from file.
}

Do I need a return after throwing the exception?

What is the case in c#?