Concrete Data Type (CDT) V/S Abstract Data Type (ADT)

Published by: Anil K. Panta

When learning about data structures, it’s important to know the difference between Abstract Data Types (ADT) and Concrete Data Types (CDT).Both are used to manage and organize data, but they are quite different in how they work and what they focus on.

What is an Abstract Data Type (ADT)?

An Abstract Data Type is a concept or blueprint that tells us what operations we can do on the data, without worrying about how those operations are done.

Key Points:

Focuses on what a data structure does
Hides internal details
Makes programming easier and more flexible

Example:

Stack (you can push or pop data, but you don’t care how it's done internally)
Queue, List, Tree, Graph

What is a Concrete Data Type (CDT)?

A Concrete Data Type is the actual implementation of the data in memory. It tells us how the data is stored and how theoperations are performed.

Key Points:

Focuses on how data is stored and manipulated
Shows actual implementation
Directly uses memory

Example:

Array (fixed-size, stored in memory)
Linked List, Struct, Class in code

Comparison Table: Abstract Data Type vs Concrete Data Type

Feature	Abstract Data Type (ADT)	Concrete Data Type (CDT)
Focus	What it does	How it works
Implementation	Not shown	Clearly defined
User knows about	Operations (e.g., insert, delete)	Data storage and memory structure
Flexibility	High – can change implementation anytime	Limited – fixed method of implementation
Examples	Stack, Queue, List, Tree, Graph	Array, Linked List, Structure

Final Summary

Abstract Data Types (ADTs) are like the idea or plan of how data works, while Concrete Data Types (CDTs) are the actual building blocks that turn the idea into reality.