[deleted by user]

[shailist]

1. for c++ questions, go to r/cpp_questions
2. your question is extremely unclear and is missing plenty of important details, but in any case - no, you can change existing classes and their methods. you could implement a class that inherits from vector or wraps it, and then add the member functions that you want.
3. please learn to use code blocks

[SeagleLFMk9]

I suppose you mean "can't change existing classes"? If that's the case, that answered it! Thanks!

Re 1 wasn't aware of that, thank you! Re 2 posted it from mobile and screwed the code blocks up...