Rama (C++ God) wrote a great article about this matter :). Please check it out here:
" → " means it is a pointer pointing to a reference on memory that might or might not exist.
“.” means it is a container that contains actual data (example struct)
:: means it is a class name or namespace.
Hello guys!
I just want to know what is the difference between → (hyphen and comparison sign to the left) and . (dot). Also I don’t really know when and how can I use :: (double colon). I’m new to this language, and I couldn’t figure it out.
Many thanks for help!
Lots of thanks to you! 
Now it is totally clean!
Great to hear that :). Happy coding!