I know how to create, write, and read form an fstream file on c++ but I don't know how to actually open that file and look at it besides on Xcode. I've seen videos on youtube where they open it through notes and you can see everything in that file but I don't know how to do that on my MacBook Pro.
Could you please clarify your problem?
Can't you use a software like TextEdit or TextWrangler or Sublime Text to open them and read their content? Do you need an hexadecimal viewer?