A12-Storing Information

Table of Contents


Objectives

  • Load and save data in text files.
  • Explore code reuse in classes.
  • Code member functions that read data from and write data to file stream parameters.
  • Overload member functions.
  • Write non-member functions that open and close file streams.

Academic Honesty

Read the Scholastic Honesty Policy and Assignment Integrity policies of the syllabus. Here are some clarifications for this particular assignment:

  • You are encouraged to work with one other student of this class following the rules of Pair Programming for Homework Assignments. If you choose to pair program, there is a bonus applied.
  • You may not give a copy of your code to your designated pair-programming partner if you did not develop the code together.
  • You may not look at another person's code until you complete and submit this assignment, except for code you develop code together with your pair-programming partner.
  • You may get help from people other than your pair-programming partner if you get stuck, but only if they do not show or tell you the code to type.
  • Do not copy code from the internet or other sources without attribution. Copying code snippets from the instructor's lesson examples without attribution is allowed.

Preparation

  1. Make sure you have completed the exercises from lesson 12.
  2. Complete the Review Exercises in CodeLab 12. These exercises will help prepare you for the problem-solving programs and should be completed first.

Project Specifications

Your solutions to these projects must use only techniques we have covered so far.

Programming Style

For all programs, remember to follow all the style rules we have covered, as well as the newer rules, including:

  1. Class naming conventions (See: Class Names)
  2. Indentation in classes and placement of curly braces
  3. Every function declaration (prototype) in the class, including constructor functions, have a function comment block
  4. Every file has a file comment block
  5. No magic numbers (See: No Magic Numbers)

Image
Image source: Ed Parrish

Project 1: File Worksheet

Files are a way to store data that is retained even after a program ends or a computer is turned off. To save data we write to a file. To recover the data, we read from the file.

Use this worksheet to improve your understanding of files, vectors and functions. Refer to lesson 11 and lesson 12 for more information on files.

Project Specifications
  1. Start by downloading the files:

    Keep the same filenames and add to the existing code in filework.cpp to complete the project. Leave the existing code unchanged, except for comments as instructed.

  2. Add your name and the date to the file comment block at the top of the filework.cpp file, replacing the words Your Name with your first and last name and Date Here with the current date.
  3. No user input is required for this project and do not add any. All data is read from the files.
  4. Write the required functions as described by the function signature and comment block.

    Do NOT change any of the function signatures.

  5. Write the function definitions below main(), and their prototypes above main().
  6. Compile and run the code when finished with each function to verify correctness.

    Uncomment the function calls from main() as you progress. Do NOT change any code in main() beyond removing comments to run the code. Also, make sure you are compiling correctly:

    g++ -Wall -Wextra -Wpedantic -std=c++11 -o vectorwork vectorwork.cpp
    
  7. Submit the filework.cpp file of this project with the rest of the assignment as described in Deliverables.

    You do not need to submit the helper.cpp file as I have it already.

Hints:
  • Remember the 5 step Procedure For File I/O in lesson 11.2.5.
  • Remember that reading from a file is like reading data with cin. Solve the problem as you would by asking the user for data and then change cin to fin (or whatever stream name you chose).
  • If you get strange results reading the products.txt file, remember that fin >> can leave a newline in the input buffer and getline() stops reading when it sees a newline ('\n'). There is a fix for this in lesson 12.1.4.

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Image by Hopstarter

Project 2: Contacts File

We continue to develop out contact list manager application. We load our data from a file and save our vector of Person objects to file so the list is retained between uses of the application. The data we work with is automatically loaded when the program starts and saved when the program exits.

When developing this program, use your Person class from Assignment 9 and your Contact List code from Assignment 11. We add new files to store data for our application.

Project Specifications
  1. Using your contacts.cpp source code from the last assignment, update your application to load and save the data of your contacts list in files.

    Keep the Person class without adding non-specified variables or removing any of the required functions from the last two assignments. Adding member functions is allowed if appropriate. Make sure to correct any errors or problems identified in the last two assignments including incorrect style. Also, make sure to #include <climits> if you use INT_MAX and #include <cstdlib> if you use exit() to ensure the program compiles on all computers.

  2. Your updated program must still operate like assignment 11. You must meet all the same specifications except for those changes described below.
  3. You must name the source code file of this assignment contactfile.cpp and include all your code in this single file.

    Be careful of the spelling, including capitalization, as you will lose points for a misspelled name. Naming is important in programming.

  4. Add a second read() member function to your Person class that reads the next set of data from a file input stream and loads the data into the member variables of the Person object in the following order:
    1. name
    2. age
    3. income

    Use the following function prototype exactly for this function:

    /**
        Loads information about this Person from the file stream.
    
        @param fin A file input stream connected to the files with the
        data to load.
    */
    void read(ifstream& fin);
    

    This function is like the read() function you wrote in assignment 11, except for the use of an input stream like fin rather than cin. For an example see lesson lesson 12.3.5. Note that this function must be able to read people's names that include single or multiple words with spaces between the words. Keep the original read() function from the last assignment.

  5. Add a non-member function named loadData() to your program that loads contact data from a file and returns the loaded data in a vector of Person objects.

    Use the following prototype exactly for this function:

    /**
        Loads all contact data from the specified file name and
        returns the data in a vector of Person objects.
    
        @param list The list of contacts read from the file.
        @param fileName The name of the file from which to read.
    */
    void loadData(vector<Person>& list, string fileName);
    

    The function must call the read(ifstream&) function from the previous step. For an example of reading file data into a vector of objects, see lesson lesson 12.3.5. When opening the file, make certain to call the c_str() member function of string to ensure compatibility with C++98.

  6. Remove your hard-coded contacts and load from the data file instead. Call the loadData() function with an argument of "contacts.txt" when the program starts so that it loads the file automatically before the menu and without any user input.
  7. You must prepare and submit a contacts.txt file and your contacts.txt must follow the format of this file: contacts.txt. The data for each contact is contained in groups of three lines each in the order:
    1. person's name
    2. age in years
    3. annual income in dollars and cents

    Make sure to save contacts.txt in the UNIX file format (see the hint below) with a blank line at the end of the file. Notice that a person's names may have spaces. Thus you must use getline() to read each person's name.

  8. Add a write() member function to your Person class that writes the member variables to a file output stream in the following order, each on a new line:
    1. name
    2. age
    3. income
    Use the following function prototype exactly for this function:
    /**
        Writes information about this Person to the file stream.
    
        @param fout A file output stream connected to the file in
        which to save the data.
    */
    void write(ofstream& fout) const;
    
  9. Add a non-member function named saveData() to your program that stores a vector of Person data into a file. Use the following prototype exactly for this function:
    /**
        Writes contact data to an output file.
    
        @param list The vector of Person objects.
        @param fileName The name of the file to which to write.
    */
    void saveData(const vector<Person>& list, string fileName);
    

    This function must call the write() function from the previous step. This function is like listing to the console but calls write() instead of print(). See lessons 10.4.1 and 10.4.2 for examples of printing and listing vectors data. When opening the file, make certain to call the c_str() member function of string to ensure compatibility with C++98.

  10. Call the saveData() function when the program exits so that all the current catalog data is saved to a file named list.txt automatically without any user input.

    The output of the saveData() function must save the data in the same format as the input file. For instance, do NOT append the data and do NOT format the numbers differently. Notice the output file name is different than the input file name. The purpose of the different names is to help during program development and grading.

  11. Submit this project with the rest of the assignment as described in Deliverables.
Hints:
  • For how to save in the UNIX file format, see lesson 11.2.4. The easiest way is to download the example contacts.txt file by right-clicking and saving the link without any copy-paste. Notice that person names may have spaces.
  • For an example of reading file data into a vector of objects, see lesson 12.3.5.
  • Do not forget about using: fin >> ws to clear whitespace from the input buffer.

Extra Credit

The following are worth extra credit points:

  1. Complete the assignment using pair programming. (1 point)
  2. Write a non-member function using the following prototype in contactfile.cpp: (2 points)
    /**
        Writes a report to an output file (extra credit).
    
        @param list The vector of Person objects.
        @param fileName The name of the file to which to write.
    */
    void writeReport(vector<Person> list, string fileName);
    

    Add a new menu item 99 to main and call the writeReport() function from main() to produce another text file named report.txt formatted like the following:

    Contacts list report:
     # Name                 Age     Income
     1 Sophie Engineer       42  102280.00
     2 Emma Hacker           24   71916.00
     3 John Q Public         37   55775.37
    
    Number of contacts: 3
    

Make certain that your README.txt file describes any extra credit attempted.

Tutorial Lab

In preparation for next weeks lessons, complete the following:

  1. Read the assigned reading in the textbook
  2. Complete the Tutorial Exercises in CodeLab 12 before the specified due date.

    Refer to the assigned reading for the next lesson to help you understand the problems. Also, you can use the online lecture notes for more information as the notes become available. You can look at solutions if you miss your first few attempts and are stuck by clicking the "Solution" tab.

Grading Criteria

The instructor will evaluate your assignment using the following criteria. Thus you should check your assignment against these criteria to maximize your score.

Each criteria represents a specific achievement of your assignment and has a scoring guide. The scoring guide explains the possible scores you can receive. Some scoring guides have a list of indicators. These indicators are a sign of meeting, or a symptom of not meeting, the specific criterion. Note that a single indicator may not always be reliable or appropriate in a given context. However, as a group, they show the condition of meeting the criterion.

For information on grading policies, including interpretation of scores, see the syllabus.

Lesson Exercises

  • 2: All lesson exercises attempted and turned in
  • 1: Some lesson exercises completed and turned in
  • 0: No lesson exercises completed or turned in

File Worksheet Functionality

  • 4: All functions completed and program generates the correct output without error
  • 3: All functions completed but has a minor error
  • 2: Most functions completed or has some small errors
  • 1: Few functions completed or has many errors
  • 0: Does not compile or wrong file turned in

Contacts File Functionality

  • 10: Demonstrates mastery of the assignment
    • Applies concepts from the lessons appropriately
    • Meets all specifications (see above) with particularly elegant solutions
    • Runs to completion with no abnormal error conditions
    • Generates correct output given correct input
    • Behaves in a reasonable way in response to incorrect data
  • 8: Has all the functionality expected of the assignment
    • Demonstrates many techniques from the lesson
    • Attempts to meet all specifications (see above)
    • Implementation seems more complicated than necessary.
    • May have one minor error
  • 6: Has most of the functionality expected of the assignment
    • Demonstrates some techniques from the lesson
    • Attempts to meet all but one of the specifications (see above)
    • Implementation seems excessively complicated.
    • May have 2-3 minor errors
  • 4: Has some of the functionality expected of the assignment
    • Demonstrates some techniques from the lesson
    • Attempts to meet at least 1/2 of the specifications (see above)
    • Implementation seems excessively complicated.
    • May have more than 3 minor errors
  • 2: Serious functional problems but shows some effort and understanding
    • Attempts to meet less than 1/2 of the of the specifications (see above)
    • Has a major error or many minor errors
    • Implementation seems very convoluted
    • Demonstrates few techniques from the lesson
  • 1: Does not compile or wrong file turned in
  • 0: Does not execute, not turned in or uses techniques not covered in course

Program Style

  • 4: Code is well-documented including:
  • 3: Code has a minor documentation error
  • 2: Code has some documentation errors
  • 1: Code has many documentation errors
  • 0: No apparent attempt to follow documentation standards or write documentation comments

CodeLab and Other Tutorial Exercises

Number completed correctly / number exercises * 8 and rounded up to the nearest integer.

README.txt File

  • 2: README.txt file submitted following the instructions
  • 1: README.txt file submitted but some information was missing
  • 0: No README.txt file submitted

Total possible: 30, plus extra credit

Deliverables

Submit your assignment to Canvas, in the assignment folder that matches the name of this assignment, following the instructions for submitting homework. Include the following items for grading:

  1. README.txt file
  2. All the exercise files from Lesson 12
  3. filework.cpp
  4. contactfile.cpp
  5. contacts.txt with a list of contact data

You must submit all the files needed to complete your assignment. Your assignment must work as submitted. Remember to test and double check your files before submitting them. If you make a mistake, you can resubmit up to the deadline. If you resubmit, you must include all your assignment files in the last submission as Canvas hides prior submissions.

Last Updated: December 02 2017 @14:29:08