My knowledge in C++ is not where I want it to be.
I have done a course objectoriented C++ at the University but
I am not one of those guys that programmed all their lives.
The reason for improving my C++ skills are twofold.
I want to work as a programmer in the future and
I want to make a game in my spare time.
I need help finding excersises to do , to improve.
I thinks that's the way instead of just reading books.
I have lot of ideas concerning games, but i realize implementing them would be too difficult for me as of now.
Contrary to what you said about reading books, if you find a good c++ book and is able to do all the exercises and actually finish the book, your knowledge of the language grows that way. The way I have found best to learn any language is to read at least one book on the language, then start programming solely in that language for a week or so. I get practice by solving problems on online judges.
If you decide to use these to practice, I will suggest sticking with one or two and becoming active with that. i.e. solve past problems and try to participate in future contests. Best way to learn imo.
To stay motivated, start a blog and blog about each problem you solve - the method and logic you applied to solving it
Good blogging site: https://www.blogger.com/home
There are other ways to practice learning a language. One way as I mentioned before is to read books and solve all practice problems in the book. Other ways include becoming active on a c++ (cplusplus) forum and try to help others with problems they are facing, learning about algorithms and implementing them, come up with a faster way to sort, etc. Open your mind and you will see the endless possibilities