Understand the power of abstraction in computer science. Learn how ADTs provide a clean interface between data and operations, enabling modular and maintainable software design.

Abstract Data Types (ADT)

An Abstract Data Type (ADT) is composed of a collection of data and a set of operations on that data. It emphasizes what operations can be performed rather than how they are implemented.

ADT Components:

Declaration of data
Declaration of operations
Encapsulation of data and operations

Core ADT Concepts

Data Abstraction

Think about what you can do with data, not how it's implemented

Benefits:

Separation of concerns
Code reusability
Easier maintenance

Encapsulation

Data and operations are bundled together, hiding internal details

Benefits:

Data protection
Interface consistency
Implementation flexibility

Information Hiding

Internal representation is hidden from users

Benefits:

Security
Modularity
Reduced complexity

Array as ADT Example

Value Definition:

abstract typedef <element_type, index_type> Array

//definition clause
element_type A [max_size]
index_type i

//condition clause
index_type == integer

Implementation Requirements:

Data Representation

Must represent all necessary ADT values and be private

Algorithm for Operations

Consistent with chosen representation, private helpers

Operator Definitions:

Extract Operation (A[i]):

abstract <element_type> Extract (A, i)

Precondition: 0 ≤ i < max_size

Postcondition: Extract == A[i]

Store Operation:

abstract Store(A, i, value)

Precondition: 0 ≤ i < max_size

Postcondition: A[i] == value

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Core ADT Concepts

Data Abstraction

Think about what you can do with data, not how it's implemented

Benefits:

Separation of concerns
Code reusability
Easier maintenance

Encapsulation

Data and operations are bundled together, hiding internal details

Benefits:

Data protection
Interface consistency
Implementation flexibility

Information Hiding

Internal representation is hidden from users

Benefits:

Security
Modularity
Reduced complexity

Array as ADT Example

Value Definition:

abstract typedef <element_type, index_type> Array

//definition clause
element_type A [max_size]
index_type i

//condition clause
index_type == integer

Implementation Requirements:

Data Representation

Must represent all necessary ADT values and be private

Algorithm for Operations

Consistent with chosen representation, private helpers

Operator Definitions:

Extract Operation (A[i]):

abstract <element_type> Extract (A, i)

Precondition: 0 ≤ i < max_size

Postcondition: Extract == A[i]

Store Operation:

abstract Store(A, i, value)

Precondition: 0 ≤ i < max_size

Postcondition: A[i] == value