C++: What is the difference between public, protected, and private inheritance?

public — "is-a". protected — "implemented-as". private — "implemented-in-terms-of".

1class Base {
2public:
3    int pub;
4protected:
5    int prot;
6private:
7    int priv;
8};
9
10class Public : public Base {
11    // pub — public
12    // prot — protected
13};

• public — public stays public.
• protected — public becomes protected.
• private — public becomes private.