Data Type (DT) – Basic Building Blocks

1. Data Type (DT) → The foundation
   • Defines the kind of data that can be stored and manipulated.
   • Examples: int, char, float (primitive types).
2. User-Defined Data Type (UDT) → Extends basic types
   • Created by combining primitive data types into more complex structures.
   • Examples: struct, class, enum.
3. Abstract Data Type (ADT) → A logical concept based on UDTs
   • Specifies operations without specifying implementation details.
   • Examples: Stack, Queue, List (can be implemented in multiple ways).
4. Data Structure (DS) → A concrete implementation of an ADT
   • Provides an actual way to store and manipulate data.
   • Examples: Array-based Stack, Linked List-based Stack.

Hierarchy Representation

Data Type (DT)
    └── User-Defined Data Type (UDT)
          └── Abstract Data Type (ADT)
                └── Data Structure (DS)

Thus, you are correct in stating:

• A Data Structure is an implementation of an Abstract Data Type.
• An Abstract Data Type is a kind of User-Defined Data Type.
• A User-Defined Data Type is a specialized form of a general Data Type.