@ bloodshot: Getting a good grasp of the basics would really be best before you go into exercises, if you will. Like a calculator- basically requires loops and logic (if's or switches).
Once you get into the actual C++ part (right now its all C for you; albeit with a different syntax (cout instead of printf, it is still C) - OOP - then you'll be able to have alot of fun with the language. Classes and objects are alot of fun, if sometimes plagued by that one headache inducing logic error- if you'd like a challenging (read - you probably will not complete it fully) "challenge assignment", why don't you recreate the string class? Start small, start simple- use c-string logic (character arrays) to begin with, then work your way up from there as you learn new aspects. Just don't cheat by viewing the c-string code- you can look at the string source (its muddled enough) if you need some basic direction.