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C++ Programming: Vectors and Sorting Assignment Instructions 


This assignment utilizes a class in an application that might be useful in the “real world.” It requires the sorting of, and computation with, data stored in a vector inside of a class. In this assignment, you will design an Object-Oriented program and manipulate data using a vector within the class.


You are working for a university to maintain a list of grades and some related statistics for a student.

Class and Data members:

Create a
that stores a student’s grades (integers) in a


(do not use an array). The class should have data members that store a student’s name and course for which the grades are earned.


The class should have a
2-argument constructor
that receives the student’s name and course as parameters and sets the appropriate data members to these values.

Member Functions:

The class should have functions as follows:

1. Member functions to set and get the student’s name and course variables.

2. A member function that adds a single grade to the vector. Only positive grades are allowed. Call this function

3. A member function to
the vector in ascending order.

Feel free to use the sort function that is available in the algorithm library for sorting vectors. Here is a web page that may help:

Or, if you would prefer to write your own sort code, you may find this site to be helpful:

4. A member function to compute the average (x̄) of the grades in the vector. The formula for calculating an average is

x̄ = ∑xi / n

where xi is the value of each grade and

n is the total number of grades in the vector.

When using a vector, you can manipulate it just like an array. For a review on how to loop over an array to calculate a sum, you may find this video to be helpful:

5. A member function to determine the lowest grade in the vector and a separate member function to determine the highest grade in the vector. [Note that to receive credit for these functions, they
must contain an algorithm
to search through the vector to determine the minimum or maximum value. You cannot simply sort the vector and return the first or last data member or use the *min_element or *max_element functions.]

Hint: The following web page provides an excellent example of algorithms to find the min and max values in an array: [Look at Technique 2]

6. A member function (e.g. getNumGrades) to return the number of grades that are stored in the vector. Remember that a vector knows its own size. Therefore, you
need to keep track of the number of items stored in a vector in a separate data member in the class. You also don’t want to make your vector public – it should be private. Therefore, you can create a public getNumGrades function that will simply return the size of the vector.

7. A member function to display the student’s name, course, and vector of sorted grades.

Write a program (client) that uses the class by creating a Student object

and prompting the user for a file name

. Appropriate error checking is required to ensure that the file exists and can be opened successfully. Also,
the name of the file may contain a space
; therefore, be sure to use getline instead of cin when you prompt the user to enter the name of the file.

The client should read in the file contents and store them in the object. The file will be formatted such that the first line contains the student’s name, the second line contains the course name, and each successive line contains a grade. A typical input file might contain:

John Smith

CSIS 112










Note that the file may contain any number of grades for a given course. Therefore, you need to read in and store each grade until you reach the end of the file.

The client (i.e. main()) should read in the contents of the file. After
grade is read in, it should call the
member function in the Student class to add
the new grade
(i.e. one grade at a time) to the vector. [
Do not
create a vector in main and pass the entire vector in to the
function in the Student class. Pass in only one grade at a time and allow the
function to add it to the vector of grades in the class.]

Main() should then produce a report that displays the student’s name and course, the total number of grades in the file, the lowest grade, the highest grade, the average of all the grades, and finally, a listing of all of the grades that were read in. The listing of all of the grades must be displayed in sorted order (ascending – from lowest to highest).

All output should be labeled appropriately, and validity checking should be done on input of the filename and also the grades that are read in.

If a non-numeric or negative value is encountered in the file when reading in the grades, the program should output an error message indicating that a non-numeric or negative value was found in the file,
and the entire program should then terminate.
If a non-numeric or negative value is found, consider the entire file to be corrupted and don’t try to produce any calculations nor display the contents of the vector – just end the program with an appropriate error message. [Make sure the error message is displayed long enough for the user to read it before ending the program. – you may use the
command for this. Note that there are several security and performance issues with using
commands, and you’ll learn more about these later, but for now, feel free to use the
command. ]

The executing program should look something like this:

In the screen above, notice that the average of the grades is displayed with decimal points. Whenever you are calculating a statistic like an average,
truncate the decimal portion unless you are told to do so. Imagine if the average of your grades in this class is 89.9… You definitely do
want your final grade truncated to 89. Therefore, in this assignment, do
truncate the decimal portion of the average you calculate. Remember the rules of integer division. That is, an int divided by an int is an int. Therefore, make sure to convert the numerator or denominator to a double before performing the division.

If a negative grade is read in, the program should look something like this:

If a non-numeric grade is read in, the program should look something like this:

In the screens above, notice that the program pauses long enough to read the error message and no statistics nor grades are displayed. This is accomplished through the use of the system(“pause”) command.

Additional information: File manipulations

Files were covered in your introduction to C++ programming class. However, you may not have had much experience manipulating them. To assist you in the file aspects of this program, you can view these short videos:

Working with Files

Tips for File Handling

Writing Custom File Structures

Reading Custom File Structures

Cool Program Working with Files

Finishing the Awesome Program

Reviewing the Final Program

More Additional Information: Error checking data in files

Recall from your first programming assignment that you were given the code to check for a non-numeric or negative value entered by the user. Now you are being asked to validate the data that is read in from a file.

In general, a file object behaves in the same way as
. That is, it goes into the fail state when a non-numeric is entered. Additionally, the file object has another function called
(stands for “end of file”) that indicates when the last data item has been read in.

The difference between a file object’s
function and the
function is subtle. When the last data item is read in from a file, the
function returns TRUE. That is, you have reached the end of the file. However, the
function is still FALSE at this point (that is, the file object is not yet in the fail state). However, once the program tries to read past the end of the file, the
function then returns TRUE (i.e. the file object goes into the fail state). Keep this in mind as you look at the example code below.

You may also notice in the code below that I haven’t cleared the file object out of the fail state. Again, the file object behaves just like
. As long as the file object is in the fail state, it can’t read in any new values. In your current assignment, you don’t need to clear it out of the fail state because once an invalid value is encountered in a file, you want your program to exit—not read in more values. However, if you ever want your program to continue reading from a file even after finding an invalid value in it, you need to clear the file object out of the fail state in the same way that you cleared cin out of the fail state in your first assignment using the
function: infile.clear().

Example code: (feel free to use this in your program and modify as needed)

Assume you have the following code that reads in data from a file called “integers.txt”. Each data item is supposed to be an integer.

· If the program encounters a non-numeric value, the program displays an error message and immediately ends.

· If the program encounters a negative value, the program displays an error message and immediately ends.

· If the file was empty from the beginning, the “End of file reached” message is displayed and the program ends.

· If the data item read in is good (i.e. numeric and positive), it prints out the number.

· When the last data item is read in, the program prints out the “End of file reached” message.

#include <iostream>

#include <fstream>

using namespace std;

int main()


ifstream infile; //instantiate a file object

int num{ 0 }; //variable to hold the number read in; initialized to 0“integers.txt”); //try to open the file

//An error check should go here to ensure that the file opened successfully. You should be able to figure this out by watching the video links above.

/*The following is a loop to read in all of the values in the file.

This loop executes for as long as the file object has not gone into the fail

state (caused by reading past the end of the file or reading in a non-numeric value) and as long as the last number read in is positive. Otherwise, the loop

ends, and the program ends.*/

while (! && num >= 0)


infile >> num; //read in a value from the file

/*If the file object goes into the fail state, BUT the eof has not been

reached, then the problem is due to reading a non-numeric value into

a variable designed to hold a numeric value. */

if ( && !infile.eof())


cout << “A non-numeric value was found in the file…Exiting program. ” << endl;


/*If the file object goes into the fail state, and the eof has been reached, the file object is in the fail state because the program has read past the end of the file. This can occur if the file is empty. If the file is empty and you try to read in anything, the file object immediately goes into the fail state, and the eof function returns TRUE. */

else if ( && infile.eof())


cout << “End of file reached.” << endl;


//If the number is negative…

else if (num < 0)


cout << “A negative value was found in the file…Exiting program. ” << endl;


//Otherwise, do something with the value read in, such as print it out.



cout << “The number read in was ” << num << endl;


} //end of while loop


return 0;


I encourage you to paste the code above into a C++ program and play around with it. It will help you in this assignment as well as future ones to really understand file manipulations. You can play around with various values in your textfile to witness the behavior.

I recommend using these possible test cases for the integers.txt file:

Empty file

Leave the file completely empty

File with a letter at the beginning






File with a letter at the end






File with a letter in the middle






File with a negative number at the beginning






File with a negative number at the end






File with a negative number in the middle






File with no negative numbers and no letters






By the way, please notice how many comments I put in the code above. This is how you should document your programs to receive full credit on your assignments. Documentation is essential to help other programmers decipher your code and to understand your logic.

Creating test cases like I illustrate above is also vital in industry. You always want to check your extremes (beginning and ending values) as well as values within the middle of a range. You should also test every possible scenario to avoid unexpected results (e.g. negatives, non-numerics, etc.).

Use good coding style [modular (use functions where appropriate), separate .h and .cpp class files, no globals, meaningful comments, etc.] throughout your program. Finally, make sure that you do not misspell anything in your output or prompts to the user. Users easily lose confidence in a system when they see misspelled words or grammatical errors. In short, make your program as professional as possible.


· Complete the programming assignment described above and submit your completed assignment in accordance with the assignment submission policies.

To give you an idea of the general criteria that will be used for grading, here is a checklist that you might find helpful:

Compiles and Executes without crashing

Word document contains screen shots and integrity statements

Appropriate internal documentation


No global variables

Code is modular

File is closed after use

Appropriate Pre-processing and using directives

Member functions and variables are declared with appropriate
protection (i.e. private or public)

Three separate files are created for the program: Student.h (header file), Student.cpp (class implementation file), and StudentDriver.cpp (driver file)


Class Creation

Appropriate data members are declared

Two argument constructor initializes data members

Set and get functions for data members

Get function for total number of grades

addGrade() — adds a single grade to the vector

sortGrades() – sorts vector in ascending order

averageGrades() – produces correct average

findMinGrade() and findMaxGrade()



Prompts user for file name

Appropriate error checking is in place to ensure that the file exists

Student name, Course, and Grades are correctly read in from the file and stored in the Student object

Error checking is performed on input data: It outputs appropriate error message; does not close the program until the error message can be read; indicates the problem with the invalid item.

Processing and Outputs

Student object created correctly

Ouput consists of the number of grades read in, the student name and course, the sorted vector of grades, the average of the grades, and the low and high grades for the student for the course – all formatted appropriately

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