Question

The C++ problem:

Student marks are kept in a text file as a single column. Each student may have a different number of assessments and therefore scores. The data recorded in the file for each student start with the number of scores for the student. This is followed by the student id and then several marks student scored in various assessments, one score per line. A small segment of the file might look like the following: (file name is marks.txt)

2

S1234567

55

70

4

S2222222

96

67

88

88

So, according data presented in this file segment, the first student has 2 scores, student id is S1234567, and the assessment scores are 55 and 70. The second students has 4 scores, student id is S2222222, and the assessment scores are 96, 67, 88 and 88.

It is anticipated (assumed) that the total number of scores in the marks.txt file will not exceed 100.

The program functionality:

Your program will utilise a number of user-defined functions to display data from the file, update data by adding marks for new students, as well as performing a number of other tasks including calculating the mean and median score of all marks and finding the minimum and maximum scores in the collection as well as calculating and displaying the average mark for a given student.

Your program should be modular and menu-driven as described below:

• The main() function handles all interactions with the user and other functions:
  • It displays an appropriate welcoming message introducing the program
  • Calls a function named readFile() which opens the text file marks.txt for

reading and stores all of the student marks from the file to an array (NOT A VECTOR!) namedmarksArray. The readFile()function has two parameters: one for receiving the file variable and one for the array, both receiving arguments passed by reference.

later

• It (the main function) then repeatedly calls the menu() function to display user

options, get the user selection returned by the menu() function, use a switch statement or a multi-alternative if statement to process user request by calling appropriate function

• It displays the result with an appropriate message after processing user request
• It displays a goodbye message when the user selects the Quit option (option 8) from the menu and terminates the program.

• The menu() function has no parameters. When called, it displays a menu of 8 options allowing the user to select one and returns this option to the calling main() function. The options displayed should be:

(1) Display marks
(2) Calculate mean
(3) Calculate median
(4) Find minimum
(5) Find maximum
(6) Find average for student

(7) Add new student data

(8) Quit program

• Option (1) will use a function called displayMarks() called from the main()to display the contents of the marks array on the screen in an appropriate format. The displayMarks() function has two parameters: the array and the number of values in the array.

• Option (2) will use a function called calculateMean() which is designed to calculate the mean value of all scores in marksArray and return the result to the main()

function which will then display it with an appropriate message. This function also has two parameters: the array and the number of values in the array.

• Option (3) will use a function called calculateMedian() which is designed to calculate the median value of all scores in marksArray and return the result to the main() function which will then display it with an appropriate message. The median value is calculated by finding the middle value when the values are sorted in ascending (or descending) order. When there are two middle values (as is the case when the number of values is even), then the average of the two middle values is the median value. Parameters for this function are the same as the previous function.
• Option (4) will use a function called findMinimum()which is designed to find the smallest value of all scores in marksArray and return the result to the main() function which will then display it with an appropriate message. Again, the parameters for this function are the same as the previous function.
• Option (5) will use a function called findMaximum()which is designed to find the largest value of all scores in marksArray and return the result to the main() function

which will then display it with an appropriate message. Again, the parameters for this function are the same as the previous function.

• Option (6) will use a function called findAverageForStudent()which is designed to get a student id as an argument as well as a reference to the marks data file from the main() function, open the marks.txt file, find the marks in the file for that particular student, calculate the average value and return it to the main function which will then display it with an appropriate message. The main function should be responsible for prompting the user for the student id.
• Option (7) will first use a function called updateFile() which will open the file in append mode, prompt the user for new student’s id followed by a varying number of marks received from the user, and then write the new data at the end of the file using the same format as the original file.
• Option (8) will terminate the program after displaying an appropriate goodbye message.

Answer 1

Marks.cpp

#include <iostream>
#include<fstream>
#include <string>
using namespace std;
int sz = 0;
fstream file;
void readFile(fstream *filepointer, float *marks)
{
   string line;
   filepointer->open("marks.txt");
   while (getline(file, line))
   {
       int i = stoi(line);
       getline(*filepointer, line);
       //cout<<"Reading ..."<<line<<endl;
       for (int j = 0; j < i; j++)
       {
           getline(*filepointer, line);
           marks[sz] = stof(line);
           sz = sz + 1;
       }

   }
   filepointer->close();

}
void displayMarks(float marks[], int sz)
{
   cout << "MARKS" << endl;
   for (int i = 0; i < sz; i++)
   {
       cout << marks[i] << "\t";
   }
   cout << endl;
}
float calculateMean(float marks[], int sz)
{
   float mean = 0;
   for (int i = 0; i < sz; i++)
   {
       mean += marks[i];
   }
   mean = mean / sz;
   return mean;
}
float calculateMedian(float marks[], int sz)
{
   float median = 0;
   float temp[100];
   for (int i = 0; i < sz; i++)
   {
       temp[i] = marks[i];
   }
   for (int i = 0; i < sz; i++)
   {
       for (int j = i; j < sz - 1; j++)
       {
           if (temp[j] > temp[j + 1])
           {
               float temp_val = temp[j];
               temp[j] = temp[j + 1];
               temp[j + 1] = temp_val;
           }
       }
   }
   if (sz % 2 == 1)
   {
       return (temp[(sz / 2)]);
   }

   return (((temp[(sz / 2)]) + (temp[(sz / 2) - 1])) / 2);
}
float findMinimum(float marks[], int sz)
{
   float min = 101;
   for (int i = 0; i < sz; i++)
   {
       if (marks[i] < min)
           min = marks[i];
   }

   return min;
}
float findMaximum(float marks[], int sz)
{
   float max = 0;
   for (int i = 0; i < sz; i++)
   {
       if (marks[i] > max)
           max = marks[i];
   }

   return max;
}
float findAverageForStudent(string id)
{
   float avg = 0;
   string line;
   file.open("marks.txt");
   while (getline(file, line))
   {
       int i = stoi(line);
       getline(file, line);
       //cout<<"Reading ..."<<line<<endl;
       if (line.compare(id) == 0)
       {
           for (int j = 0; j < i; j++)
           {
               getline(file, line);
               avg += stof(line);
           }
           avg = avg / i;
       }
   }
   file.close();
   return avg;
}

void updateFile(int num, string id, float *marks)
{
   file.open("marks.txt", ios::app);
   file << num << "\n";
   file << id << "\n";

   for (int j = 0; j < num; j++)
   {
       file << marks[j] << "\n";
   }

   file.close();
}
int main()
{
   bool flag = true;
   int choice = 0;
   float marks[100];
   readFile(&file, marks);
   while (flag)
   {
       cout << "(1) Display marks\n(2) Calculate mean\n(3) Calculate median\n(4) Find minimum\n(5) Find maximum\n(6) Find average for student\n(7) Add new student data\n(8) Quit program\n";
       cin >> choice;
       switch (choice)
       {
       case 1: {
           displayMarks(marks, sz);
           break;
       }
       case 2: {
           cout << "MEAN: " << calculateMean(marks, sz) << endl;
           break;
       }
       case 3: {
           cout << "MEDIAN: " << calculateMedian(marks, sz) << endl;
           break;
       }
       case 4: {
           cout << "MIN: " << findMinimum(marks, sz) << endl;
           break;
       }
       case 5: {
           cout << "MAX: " << findMaximum(marks, sz) << endl;
           break;
       }
       case 6: {
           string id;

           cout << "Enter student ID" << endl;
           cin.ignore(1, '\n');
           getline(cin, id);
           cout << "Avg_of_Student: " << id << " --- " << findAverageForStudent(id) << endl;
           break;
       }
       case 7: {
           int num;
           cout << "Enter num of entries for the student" << endl;
           cin >> num;
           string id;
           cout << "Enter student ID" << endl;
           cin.ignore(1, '\n');
           getline(cin, id);
           cout << "Enter marks" << endl;
           float *marks = new float[num];
           for (int i = 0; i < num; i++)
           {
               cin >> marks[i];
           }
           updateFile(num, id, marks);
           break;
       }
       case 8: {
           file.close();
           flag = false;
           cout << "GOODBYE" << endl;
           break;
       }
       default:cout << "Not a valid option" << endl;
       }

   }
}

INPUT:

OUTPUT:

OUTPUT:

(1) Display marks
(2) Calculate mean
(3) Calculate median
(4) Find minimum
(5) Find maximum
(6) Find average for student
(7) Add new student data
(8) Quit program
1
MARKS
55 70 96 67 88 88
(1) Display marks
(2) Calculate mean
(3) Calculate median
(4) Find minimum
(5) Find maximum
(6) Find average for student
(7) Add new student data
(8) Quit program
2
MEAN: 77.3333
(1) Display marks
(2) Calculate mean
(3) Calculate median
(4) Find minimum
(5) Find maximum
(6) Find average for student
(7) Add new student data
(8) Quit program
3
MEDIAN: 79
(1) Display marks
(2) Calculate mean
(3) Calculate median
(4) Find minimum
(5) Find maximum
(6) Find average for student
(7) Add new student data
(8) Quit program
4
MIN: 55
(1) Display marks
(2) Calculate mean
(3) Calculate median
(4) Find minimum
(5) Find maximum
(6) Find average for student
(7) Add new student data
(8) Quit program
5
MAX: 96
(1) Display marks
(2) Calculate mean
(3) Calculate median
(4) Find minimum
(5) Find maximum
(6) Find average for student
(7) Add new student data
(8) Quit program
6
Enter student ID
S1234567
Avg_of_Student: S1234567 --- 62.5
(1) Display marks
(2) Calculate mean
(3) Calculate median
(4) Find minimum
(5) Find maximum
(6) Find average for student
(7) Add new student data
(8) Quit program
7
Enter num of entries for the student
2
Enter student ID
S23345354
Enter marks
45
67
(1) Display marks
(2) Calculate mean
(3) Calculate median
(4) Find minimum
(5) Find maximum
(6) Find average for student
(7) Add new student data
(8) Quit program
8
GOODBYE