are there any free online available books i should refer for c++ along with sololearn?

Answer 1

Search online for pdf book called "Thinking in C++". There are a few of those, I think 2 volumes. Full pdf books, over 500 pages.
And this one - The C++ Programming Language 4th Edition by Bjarne Stroustrup

Answer 2

Books especialy ... probably. But if you just try to find other tutorial for this language, Google is your friend :
http://www.cplusplus.com/doc/tutorial/
http://www.learncpp.com/
https://docs.unrealengine.com/latest/INT/Programming/Tutorials/

Answer 3

You should have a look at e. balaguruswamy for c++ it is a nice book for learning c++

Answer 4

let us c++ by Yashvant Kanetkar

Answer 5

object oriented programming with C++ by Balaguruswamy