Question

what is the concept of inheritance and aggregation in c++?

Answer 1

1) Intuitive Understanding
if we have a class called A, which is
class A{...};
inheritance like this:
class B: public A {...};
aggregation like this:
class B{ A some_a; };

2) Concept
Firstly, one of aims of Inheritance and Aggregation is to compartmentalize and reuse code, but they still have differences between each others.

Inheritance imply a "is-a" or "is-kind-of" relationship between subclass and super class, e.g. Square is kind of Rectagle,so you can design like:
class Square: pulic Rectangle{...};

Aggregation imply a "has-a" relationship between two classes, e.g. a group of person is aggregated by many persons, so you can design like:
class PersonGroup { PersonList many_many_Person;};

in sum, there are many differences bwtween them, whether in semantics or in implement, i hope that i can help you .
if i have some error, please let me kown, thank you.
btw, it's better if my poor english won't confuse you.