Data Abstraction Chapter 2
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Questions and Answers

What is the purpose of constructors in abstract data types?

  • To build the abstract data type (correct)
  • To retrieve information from the data type
  • To modify the existing data type
  • To delete the data type

What information does the city object hold?

  • The city's latitude and longitude only
  • Only the city's name
  • The city's name, latitude, and longitude (correct)
  • The city's longitude only

What is the purpose of selectors in abstract data types?

  • To retrieve information from the data type (correct)
  • To delete the data type
  • To build the abstract data type
  • To modify the existing data type

How do you create a city object?

<p>Using a function like city = makecity (name, lat, lon) (C)</p> Signup and view all the answers

Who defines the functions for the end user?

<p>Someone else (B)</p> Signup and view all the answers

What is assumed about the functions in the abstract data type?

<p>The end user doesn't know how they were implemented (D)</p> Signup and view all the answers

What is the role of constructors and selectors in abstract data types?

<p>Constructors build the data type, selectors retrieve information (A)</p> Signup and view all the answers

What is the abstraction level of the city object?

<p>Abstract data type (B)</p> Signup and view all the answers

What is the purpose of naming the parts of a multi-item object?

<p>To make it easier to access each item (D)</p> Signup and view all the answers

What is the main difference between a list and a multi-item object like a Person?

<p>A list allows direct access to each item, while a Person object does not (D)</p> Signup and view all the answers

What is an advantage of using named parts in a multi-item object?

<p>It makes the code more readable (A)</p> Signup and view all the answers

What is the purpose of the 'id' attribute in the Person object?

<p>To store a unique identifier for the person (D)</p> Signup and view all the answers

How is the Person object represented pictorially?

<p>As a diagram with named parts (D)</p> Signup and view all the answers

What is the main benefit of using a multi-item object like a Person?

<p>It allows for more organized and structured data (D)</p> Signup and view all the answers

What is the purpose of the constructor function makecity()?

<p>To create an object of the city (B)</p> Signup and view all the answers

What do the functions getlat() and getlon() retrieve from the city object?

<p>The city's latitude and longitude (D)</p> Signup and view all the answers

What is the purpose of the distance() function?

<p>To compute the distance between two city objects (D)</p> Signup and view all the answers

What does the := symbol represent in the pseudo code?

<p>An assignment operator (A)</p> Signup and view all the answers

What is the term used to describe the functions getlat() and getlon()?

<p>Selectors (D)</p> Signup and view all the answers

What is the formula used to compute the distance between two city objects?

<p>(lt1 - lt2)**2 + (lg1 - lg2)**2)**1/2 (C)</p> Signup and view all the answers

What is the purpose of the lt and lg variables in the distance() function?

<p>To store the city's latitude and longitude (A)</p> Signup and view all the answers

What is the data type of the city object?

<p>Not specified in the pseudo code (C)</p> Signup and view all the answers

What is the primary goal of data abstraction?

<p>To define an abstract data type and separate it from its representation (B)</p> Signup and view all the answers

What is a key component of an abstract data type (ADT)?

<p>A collection of constructors and selectors (D)</p> Signup and view all the answers

What is the purpose of selectors in an abstract data type?

<p>To extract individual pieces of information from an object (C)</p> Signup and view all the answers

What is the relationship between the part of a program that operates on abstract data and the part that defines a concrete representation?

<p>They are connected by a small set of functions that implement abstract data in terms of the concrete representation (A)</p> Signup and view all the answers

What is a rational number an example of?

<p>A sub-class of real numbers (A)</p> Signup and view all the answers

What is the purpose of the example of rational numbers in the context of data abstraction?

<p>To illustrate the technique of data abstraction (C)</p> Signup and view all the answers

What is the result of constructors in an abstract data type?

<p>An object that bundles different pieces of information (A)</p> Signup and view all the answers

What is the role of a small set of functions in data abstraction?

<p>To implement abstract data in terms of the concrete representation (C)</p> Signup and view all the answers

What is an Abstract Data Type (ADT)?

<p>A type that defines a set of values and operations (D)</p> Signup and view all the answers

What does the definition of an Abstract Data Type (ADT) specify?

<p>What operations will be performed (C)</p> Signup and view all the answers

What is the process of providing only the essentials and hiding the details called?

<p>Abstraction (A)</p> Signup and view all the answers

What is the main difference between a concrete and abstract implementation?

<p>The level of abstraction (A)</p> Signup and view all the answers

What is an example of a concept related to Abstract Data Types?

<p>Data Structures (D)</p> Signup and view all the answers

What is the purpose of Abstraction in Data Structures?

<p>To hide the implementation details (D)</p> Signup and view all the answers

What is the benefit of using Abstract Data Types (ADTs)?

<p>Implementation independence (A)</p> Signup and view all the answers

Study Notes

Data Abstraction

  • Data Abstraction is a process of providing only the essential features and hiding the details.
  • It gives an implementation-independent view.

Abstract Data Types (ADT)

  • ADT is a type (or class) for objects whose behavior is defined by a set of values and a set of operations.
  • The definition of ADT only mentions what operations are to be performed, but not how these operations will be implemented.
  • It does not specify how data will be organized in memory and what algorithms will be used for implementing the operations.

Difference between Concrete and Abstract Implementation

  • Concrete implementation is implementation-dependent.
  • Abstract implementation is implementation-independent.

Constructors and Selectors

Constructors

  • Constructors are functions that build the abstract data type.
  • They create an object, bundling together different pieces of information.

Selectors

  • Selectors are functions that retrieve information from the data type.
  • They extract individual pieces of information from the object.

Example: City Abstract Data Type

  • The city object will hold the city's name, and its latitude and longitude.
  • Constructors: city = makecity (name, lat, lon)
  • Selectors: getname(city), getlat(city), getlon(city)

Data Abstraction in Programming

  • Data abstraction is supported by defining an abstract data type (ADT), and constructors and selectors.
  • The two parts of a program are: the part that operates on abstract data, and the part that defines a concrete representation, connected by a small set of functions that implement abstract data in terms of the concrete representation.

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Learn about abstract data types and abstraction in programming. Understand the concept of ADT and its importance in programming.

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