Subex Interview Procedure

I attend for interview in subex.they asked me only basic concepts in c and c++.u dont bather abt that what u r telling say confidenly.
they asked me
1.define virtual function with example
2.what is friend construcetr
3.diffrence b/w function and macro
4.write a pgm for 2 count no of 1 bits presents on given number
5.what arry to pointer and pointer to array,,is there any diffrece
like this simple basics
ok