What is the difference between basic data types and derived data types and user defined data types in C plus plus?

Answer 1

By basic types you presumably mean primitive types or built-in types. These include char, int, long, short, wchar_t, float, double and bool, amongst others. Most are simply variations of each other, but their lengths are implementation dependant. The only exception is char which is always 1 byte in length.

User-defined types are those you yourself define or are defined for you. These include typedefs, enums, classes, structs and unions, but can also include some implementation-specific built-in types and all third-party types. Regardless, all user-defined types build upon the primitive data types or other user-defined types. In the case of class and struct types, methods (or member functions) can be associated with those types, thus combining data and the specific methods that act upon that data into a single entity. Objects are specific instances of a class or struct.

A derived type is a class (or struct) which inherits from another class (or struct). A derivative cannot inherit from a primitive, enum or union. Derived types are also, by definition, user-defined types.