https://www.stroustrup.com/bs_faq.html#from-Smalltalk
> C++ got its Object-Oriented concepts from Smalltalk?
> No. C++ got the key notions of classes, derived classes, virtual functions (in other words, the notions of encapsulation, inheritance and polymorphism) from Simula just like Smalltalk did. In terms of family relationships, C++ and Smalltalk are siblings.
And C++ derives much from Simula which comes from Algol. And C derives much from Algol. And link between C and C++ is kinda obvious!
But I know at the University of Oslo there has been some annoyance that Simula’s place in programming history is so unknown while smalltalk has this outsized role.
Smalltalk definitely inspired Objective-C but C++ is clearly derived from Simula. As a fellow Scandinavian Bjarne was well aware of Simula and an active user of it.
Every time you write "protected" or "virtual", that's Simula speaking.