C++ questions -1

1. Difference between a "assignment operator" and a "copy constructor" ****
2. what is difference between constructor and destructor
3. What is the difference between an object and a class?
4. What is "strstream”?
5. What is a class?
6. What are virtual functions?
7. How is static variable stored in the memory? ( if there are 2 functions in a file,and the static variable name is same (ex var) in both the function. how is it keep seperately in the memory).
8. What are the things contains in .obj file? (Compiled result of .cpp file)
9. What is importance of const. pointer in copy constructor?
10. What is the Basic nature of "cin" and "cout" and what concept or principle we are using on those two?
11. What is friend function?
12. Why array index starts from 0[zero] only?
13. Why always array starts with index 0
14. What is the difference between Object and Instance?
15. What is an algorithm (in terms of the STL/C++ standard library)?
16. What is abstraction?
17. What are virtual functions?
18. What is a scope resolution operator?
19. What do you mean by pure virtual functions?
20. What is a memory leak? How can we avoid it?