Homework作业 | 代做Project | Assignment代写 | Database代写 – 这是一个典型的数据库题目
CSCI 1300 – Starting Computing Instructor: Fleming
Problem Set
**All the examples and values used in examples are imaginary and randomly generated. In part 3 you will streamline your implementation with the addition of a library class. This class will centralize many of the methods you implemented in parts 1 and 2 and provide more functionality, including the ability to recommend books based on the similarity of two users. Specifications Create a new class Library. Define the class in a header file and implement the class in a cpp file. The Book and User classes from Homework 7 will be part of Homework 8 as well In main() create an instance of Library object and a menu as specified Students should have seven files (Book.h, Book.cpp, User.h, User.cpp, Library.h, Library.cpp, Hmwk8.cpp) The name of each member function should be exactly as specified. If you modify the function names your solution will not pass the autograder.
Library Class
**You should have separate files for class definition and implementation: Library.h and Library.cpp Create a class Library, with separate interface and implementation, comprised of the following attributes: Data members (private): Book array: books An array of Book objects User array: users An array of User objects int: numBooks Number of books in the database (library) int: numUsers Number of users in the database (library) int: sizeBook The capacity of the books array (200). Constant int: sizeUser The capacity of the users array (200). Constant Member functions (public): Default constructor Sets both numBooks and numUsers to value 0. readBooks(string) Takes a string (the name of the file to be read) and populates the books array. Returns the total number of books in books array as an integer readRatings(string) Takes a string (the name of the file to be read) and populates the users array. Returns the total number of users in users array as an integer printAllBooks() Prints all books stored in books array. getCountReadBooks(string) Takes a string (username) and returns the number of books read by that user as an integer. calcAvgRating(string) Takes a string (the title of a book) and returns the average rating of the specified book as a double addUser(string) Takes a string (username) and returns True if the username is successfully added to the database. Otherwise, returns False .
checkOutBook(string, string, int) Takes two strings and an integer for username, title of book, and a new rating, respectively (in this order). Returns True if the rating is successfully updated. Otherwise, returns False . viewRatings(string) Takes a string (username) and prints all the books a user has provided ratings for. getRecommendations(string)Takes a string username and prints the first 5 book recommendations from the most similar (other) user. It is advisable to write your own test cases for each class. Test your class in Cloud9 before submitting to the autograder, as the autograder has a submission limit of 20 tries every 24 hours .
Problem 1 – the member function readBooks
The member function readBooks populates an array of Book objects with the title and author data found in a file similar to the file books.txt. The array of Book objects is one of the data members of the Library class. This function should: Accept one input argument: string: the name of the file to be read Use ifstream, split(), and getline to read and parse data from the file. For each line in the file: fill in the author and title data members for a Book object, at the appropriate index in the array of Book objects. Also: Update the total number of books in the system(from all the files read so far, see the Important note below) Return the total number of books in the system, as an integer. If the file contains more books than empty slots available in the books array, only write enough books so that you do not exceed the capacity of the array. If the file cannot be opened, return – Important: when testing your readBooks function, make sure it supports multiple reads from different .txt files in a row. For example, you should be able to call the function to read the file books1.txt , and then call the function again to read the file
book2.txt . The result should be an array of Book objects, with the books from the first file, followed by the books from the second file.
Problem 2 – the member function readRatings
The member function readRatings populates an array of User objects with the user name and the ratings data found in a file similar to the file ratings.txt. The array of User objects is one of the data members of the Library class. This function should: Accept one input argument: string: the name of the file to be read Use ifstream, split(), and getline to read and parse data from the file. For each line in the file: fill in the username and ratings data members for a User object, at the appropriate index in the array of User objects. Also: Update the total number of users in the system(from all the files read so far, see the Important note below) Return the total number of users in the system, as an integer. If the file contains more users than empty slots available in the users array, only write enough books so that you do not exceed the capacity of the array. If the file cannot be opened, return – Important: when testing your readRatings function, make sure it supports multiple calls in a row. For example, you should be able to call the function to read the file ratings1.txt , and then call the function again to read the file ratings2.txt . The result should be an array of User objects, with the users from the first file, followed by the users from the second file. Expected output: cynthia… diane… joan… barbara… (etc.)
Problem 3 – the member function printAllBooks
The member function printAllBooks prints the list of all the books in the database (library). This function should: Accept no arguments Not return anything If the program has not read any books files or any ratings files, print the following message: Database has not been fully initialized Otherwise, print Here is a list of books, followed by each book in the following format
by
Expected output (assuming you have read the data only from books.txt)
Here is a list of books
The Hitchhiker's Guide To The Galaxy by Douglas Adams
Watership Down by Richard Adams
The Five People You Meet in Heaven by Mitch Albom
Speak by Laurie Halse Anderson
(etc.)
Problem 4 – the member function getCountReadBooks
The member function getCountReadBooks determines how many books a particular user has read and reviewed. This function should: Accept one argument: string: username Return the number of books read/reviewed by the specified user, as an integer. If the program has not read any books files or any ratings files, it should return – after printing the following message: Database has not been fully initialized If the database is initialized (at least one file of books and at least one file of ratings has been read), but the user name is not found, return -2 after printing the following message :
Problem 5 – the member function calcAvgRating
The member function calcAvgRating returns the average (mean) rating for a particular book. This function should: Accept one argument: string: book title Return the average rating of the specified book as a double If the program has not read any books files or any ratings files, it should return – after printing the following message: Database has not been fully initialized If the database is initialized (at least one file of books and at least one file of ratings has been read), but the book is not found, return -2 after printing the following message:
Problem 6 – the member function addUser
The member function addUser adds a new user to the database. This function should: Accept one argument: string: user name Fill in the username and ratings data members for a User object, at the appropriate index in the array of User objects. : Update the total number of users in the system(from all the files read so far, see the Important note below) The name of the user is case insensitive (e.g. Ben. BEN, ben are all same as ben) Return True if the user is successfully added. If the user already exists in the database, print the following message and return False
Problem 7 – the member function checkOutBook
The member function checkOutBook updates the rating of the book for the user. This function should: Accept three arguments in this order string : username string: book title int: new rating Find the index of the user and the index for the book, then update the new rating if the new rating value is valid. The rating scheme follows the one provided in homework 6. Rating Meaning 0 Did not read 1 Hell No – hate it!! 2 Dont like it. 3 Meh – neither hot nor cold 4 Liked it! 5 Mind Blown – Loved it! If the program has not read any books files or any ratings files, it should return False after printing the following message: Database has not been fully initialized If the rating is successfully updated, then returns True . Otherwise, it shows one (or more) of the following messages in the given order and return False . If the user is not found:
Problem 8 – the member function viewRatings
The member function viewRatings prints all the books a user has provided ratings for. Recall that a rating of 0 means a user has not rated that book and hence shouldnt be displayed. This function should: Accept one input argument: string: username Not return anything. If the program has not read any books files or any ratings files, print the following message: Database has not been fully initialized If the user is not found in the database, print:
Title : The Five People You Meet in Heaven Rating : 2
(…)
Problem 9 – the member function getRecommendations
The member function getRecommendations will recommend book titles a user might enjoy, based on the users similarity of ratings with another user. This function should: Accept one input argument: string: username
Not return anything. If the program has not read any books files or any ratings files, it should print the following message: Database has not been fully initialized If the database is initialized (at least one file of books and at least one file of ratings has been read), but the user name is not found, it should print the following message :
- Find the most similar user to ben. Lets say we found claire to be most similar.
- Recommend to ben the first 5 books in the database claire has rated with a rating of 3, 4 or 5, that ben has not yet read (rating 0) If there are less than 5 books to recommend, recommend as many as possible. ben will be presented with 0 to 5 recommendations. To find out who the most similar user is to ben, we need to compare bens ratings with the ratings from all the other users. We need to look at differences in the rating values between the two users for a certain book, add them up, and come up with a similarity value . The user who has the smallest similarity value , will be the user most similar to ben. Note 1: A new user, who has not rated any books, cannot be chosen as the most similar user. We recommend you use the getCountReadBooks function to weed out the new users. Note 2: You can assume there will be no ties between two users. The similarity metric you should use is the sum of squared differences (SSD) . The sum of squared differences is calculated by summing the squares of the differences between corresponding elements in two ratings arrays from two users. Follow the example below. Let A represent ben’s ratings, and B represent claire’s ratings. A i is ben’s rating for book i , and B i is claire’s rating for book i
SSD = ( A )
i
i
B
i
2
For example:
john s ratings : [ 0 , 1 , 3 , 5 ] (^) claire s ratings : [ 3 , 0 , 5 , 0 ] (^) SSD = ( 0 3 ) ( 1 0 ) ( 3 5 ) ( 5 0 ) 2
- 2
- 2
- (^2) SSD = ( 3 ) 2 + ( 1 ) 2 + ( 2 ) 2 + ( 5 ) 2 SSD = 9 + 1 + 4 + 25 = (^39) Users with very different ratings will get a high SSD. john s ratings : [ 5 , 1 , 0 , 0 , 5 ] (^) david s ratings : [ 1 , 5 , 0 , 5 , 1 ] (^) SSD = ( 5 1 ) 2 + ( 1 5 ) 2 + ( 5 0 ) 2 + ( 5 1 ) 2 SSD = 4 2 + 4 2 + 5 2 + 4 2 SSD = 16 + 16 + 25 + 16 = (^73) Two users with very similar ratings will get a low SSD. john s ratings : [ 5 , 0 , 5 , 3 ] claire s ratings : [ 5 , 0 , 4 , 2 ] (^) (^) SSD = ( 5 5 ) 2 + ( 5 4 ) 2 + ( 3 2 ) 2 SSD = 0 2 + 1 2 + 1 2 SSD = 0 + 1 + 1 = (^2) For example (this example is different than the data in ratings.txt): Let’s say we’re generating recommendations for John. Here are the books: Douglas Adams,The Hitchhiker’s Guide To The Galaxy Richard Adams,Watership Down Mitch Albom,The Five People You Meet in Heaven Laurie Halse Anderson,Speak
Liz: [5, 0, 5, 3] John: [5, 0, 3, 0] David: [4, 1, 0, 5] To generate recommendations for John:
1. find the most similar user John has a SSD of 13 with Liz and an SSD of 36 with David, so John is more similar to Liz. 2. find 10 books Liz (the most similar user) has rated as a 3, 4, or 5 that John has not yet read (rating 0) We look at Liz’s list to find books that she’s rated that John hasn’t rated yet: Liz has rated The Hitchhiker’s Guide To The Galaxy as a 4, but John has already rated this book. Liz has rated Watership Down as 1, but the rating is too low. Liz hasnt rated The Five People You Meet in Heaven Liz has rated Speak as a 5. John hasn’t read that book yet, so we add it to the list of recommendations. There are no more books that Liz has rated, so we’re done. Our final list of recommendations will be: speak by laurie halse anderson Here are examples of output in different situations: If there are no books to recommend for a certain user, print the following: There are no recommendations for
Driver function
In addition to the menu functionality used in the Homework 6 and 7, we need to add 4 more options. You can find the updated displayMenu function in Hmwk8.cpp on Moodle. Menu options:
- Read book file Prompt the user for a file name Pass the file name to your readBooks function. After the function returns, print the total number of books in the database: Total books in the database:
If no books are saved to the database due to wrong file name, then print the following message: No books saved to the database - Read user file Prompt the user for a file name. Pass the file name to your readRatings function After the function returns, print the total number of users in the database: Total users in the database:
If no books are saved to the database due to wrong file name, then print the following message: No users saved to the database - Print book list Call your printAllBooks function.
- Find number of books user rated Prompt the user for a username. Pass the username to your getCountReadBooks function If the user exists in the system, print the result in the following format:
<name> rated <numBookRead> books
- Get average rating Prompt the user for a title. Pass the title to your calcAvgRating function If the title exists in the database, print the result in the following format: The average rating for
is Note: is a double with 2 decimal points. - Make a new account Prompt the user for a username: Enter a username: Pass the username to your addUser function Based on the return value from the addUser function, you need to print a message. If the user has successfully been added to the database, print: Welcome to the library
If the user was not added to the database, print: could not be added in the database - Check Out Book Prompt the user for the username, the title of a book, and the new rating Enter a username: Enter a book title: Enter a rating for the book: Pass the username, the title, and the new rating to your checkOutBook function Based on the return value from the checkOutBook function, you need to print a message. If the book has successfully been read and rated, print: We hope you enjoyed your book. The rating has been updated If the book has not successfully been read and rated, print:
<user_name> could not check out <book_title>
- View Ratings Prompt the user for a username Enter a username: Pass the username and the title to your viewRating function
- Get recommendations Prompt the user for a username Enter a username: Pass the username to your getRecommendations function 10.Quit