CODE IN C++: The University of Southern North Dakota Testing department needs to

ID: 3838517 • Letter: C

Question

CODE IN C++:

The University of Southern North Dakota Testing department needs to write a grading program for multiple choice test. It should be capable of grading tests with up to 50 questions and for any number of students. The program should grade individual exams and calculate the grade for the student based on the number of questions, each being the same value out of 100. For example, if there are 25 questions each is worth 4.

The program must also determine how many times each score was earned on the test. This is a count or frequency. The program must should show the number of students graded and the class average.

The program should have

a single function (called with different parameters) to read the answer key and the student responses. The arrays are the same size and data type so only one function is needed.

a function that take the answer key and student response as parameters and then computes the score for that student. The score is returned as int by the function.

an input file. The program asks the user for the name of the file. The file name is entered at the keyboard. All subsequent data is read from the file.

a score frequency count. Every time a score is computed increment a counter for that value. Any score from 0 to 100 is possible (integer only), so the program needs 101 counters!

Behavior not assigned to functions may be done in main.

The program will accept the input file name from the keyboard after prompting the user for the file name.

The first line in the input files contains the number of questions on the exam, the second the answer key, and all following lines contain the student ids and responses to the questions.

The input shown here

2 1 1 3 4 4 5 3 2 1 2 4 5 2 1 1 3 4 4 2

12345 2 1 1 1 4 4 3 3 2 1 2 4 5 2 2 1 4 4 4 3

23456 2 1 1 2 3 4 5 3 2 1 2 4 5 2 1 2 3 4 4 1

14567 1 2 1 3 4 4 3 3 2 1 2 4 5 2 2 1 4 4 4 2

15678 2 1 2 3 3 4 5 3 1 1 3 4 5 2 1 1 3 4 4 2

16789 2 1 1 3 4 4 5 3 2 1 2 4 5 2 1 1 3 4 4 2

17890 2 1 1 3 4 4 5 3 2 1 2 4 5 2 2 1 4 4 4 3

12245 1 2 1 3 4 4 3 3 2 1 4 4 5 2 2 1 4 4 4 2

12256 2 1 2 3 3 4 5 3 1 1 2 4 5 2 1 1 3 4 4 2

22345 2 1 1 2 3 4 5 3 2 1 2 4 5 2 1 2 3 4 4 1

22456 1 2 1 3 4 4 3 4 2 1 2 4 5 2 2 1 4 4 4 2

13244 2 1 1 3 3 4 5 3 1 1 3 4 5 2 1 1 3 4 4 2

22458 2 2 1 3 4 4 5 3 2 1 2 4 5 2 1 1 3 4 4 2

23678 2 1 3 3 4 4 5 3 2 1 2 4 5 2 2 4 4 4 4 3

24567 2 1 2 3 3 4 5 3 2 1 2 4 5 1 1 2 3 3 4 1

11412 2 1 2 3 3 4 5 3 1 2 2 4 4 2 1 1 3 4 4 2

produces this output:

Enter file name:scantron.txt

Student ID Score

===================

12345 75

23456 80

14567 75

15678 80

16789 100

17890 85

12245 70

12256 85

22345 80

22456 70

13244 85

22458 95

23678 75

24567 70

11412 75

===================

Tests graded = 15

===================

Score Frequency

===================

100 1

95 1

85 3

80 3

75 4

70 3

===================

Class Average = 80

the solution to this is:

#include <iostream>

#include <fstream>

#include <iomanip>

#include <string>

using namespace std;

const int MAX_SCORE = 100;

bool readarray(fstream &file, int array[], int size){

for(int i=0; i< size; i++)

file >> array[i];

return file.eof();

}

int gradeOneTest(int key[], int answers[], int size){

int misses = 0;

for(int i=0; i< size; i++)

if(key[i] != answers[i])

misses++;

return MAX_SCORE - (MAX_SCORE/size) * misses;

}

int main(){

fstream infile;

int key[50], answers[50], num_questions;

int frequency[101] = {0};

int studentID, score, numTests=0;

double average=0;

string filename;

cout << "Enter file name:";

cin >> filename;

infile.open(filename, ios::in);

infile >> num_questions;

readarray(infile, key, num_questions);

cout << "Student ID Score" << endl;

cout << "===================" << endl;

while(!infile.eof()){

infile >> studentID;

readarray(infile, answers, num_questions);

score = gradeOneTest(key, answers,num_questions) ;

frequency[score]++;

average += score;

cout << studentID << setw(12) << score << endl;

numTests++;

}

cout << "===================" << endl;

cout << "Tests graded = " << numTests << endl;

cout << "===================" << endl;

cout << "Score" << setw(14) <<"Frequency" << endl;

cout << "===================" << endl;

for(int i=100;i>0;i--)

if(frequency[i]!=0)

cout << setw(3) << i << setw(12)<< frequency[i] << endl;

cout << "===================" << endl;

cout << "Class Average = " << average / numTests << endl;

return 0;

}

Rewrite the Scantron program so that it uses a class called Student to hold the student ID and grade.

Make a second class called Class that contains an array of the Student class and an integer that stores how many Student class objects are in the array.

As each student is ID is read from the file add them to a student class in the array of student class.

As the grade for each student is calculated add it to the student’s class.

Adjust the rest of the program to use the array of classes in place is single integer values.

Sort the class of student structs in descending order by grade.

Do not output anything until all students have been processed and sorted.

Do not use anything from the STL. Do not use any sort routine other than one you code from scratch , you can use a bubble sort

Explanation / Answer

Here's the code that uses structs Student and Class:

#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>

using namespace std;

const int MAX_SCORE = 100;

class Student {
public:
int id;
int grade;
Student() {
id = -1;
grade = -1;
}
};

class Class {
public:
Student* students;
int students_count;
Class() {
students_count = 0;
}
};

bool readarray(fstream &file, int array[], int size){
for(int i=0; i< size; i++)
file >> array[i];
return file.eof();
}

int gradeOneTest(int key[], int answers[], int size){
int misses = 0;

for(int i=0; i< size; i++)
if(key[i] != answers[i])
misses++;
return MAX_SCORE - (MAX_SCORE/size) * misses;
}

int main() {
fstream infile;
int num_questions;

string filename;

cout << "Enter file name:";
cin >> filename;

infile.open(filename, ios::in);

infile >> num_questions;
int key[num_questions], answers[num_questions];
readarray(infile, key, num_questions);

Class c;

while(!infile.eof()){
int studentID;
infile >> studentID;
readarray(infile, answers, num_questions);
int score = gradeOneTest(key, answers,num_questions) ;

Student s;
s.id = studentID;
s.grade = score;

if(c.students_count == 0) {
c.students = new Student[1];
c.students_count = 1;
c.students[0] = s;
} else {
c.students_count++;
Student* newArray = new Student[c.students_count];
// we are going to use insertion sort to sort the students' array
bool inserted = false;
for(int i=0; i<c.students_count-1; i++) {
if(inserted) {
newArray[i+1] = c.students[i];
}
else if(c.students[i].grade > s.grade) {
newArray[i] = c.students[i];
}
else {
newArray[i] = s;
newArray[i+1] = c.students[i];
inserted = true;
}
}
if(!inserted) {
newArray[c.students_count-1] = s;
}
delete[] c.students;
c.students = newArray;
}
}

int frequency[101] = {0};
double average=0;
for(int i=0; i<c.students_count; i++) {
frequency[c.students[i].grade]++;
average += c.students[i].grade;
}
cout << "Student ID Score" << endl;
cout << "===================" << endl;
for(int i=0; i<c.students_count; i++) {
cout << c.students[i].id << setw(12) << c.students[i].grade << endl;
}
cout << "===================" << endl;
cout << "Tests graded = " << c.students_count << endl;
cout << "===================" << endl;
cout << "Score" << setw(14) <<"Frequency" << endl;
cout << "===================" << endl;
for(int i=100;i>0;i--)
if(frequency[i]!=0)
cout << setw(3) << i << setw(12)<< frequency[i] << endl;
cout << "===================" << endl;
cout << "Class Average = " << average / c.students_count << endl;
return 0;
}

Note: We have used insertion sort to sort the students by grades, as we read the each student information from the file.

OUTPUT, for this version of the code:

Student ID Score

===================

16789 100

22458 95

13244 85

12256 85

17890 85

22345 80

15678 80

23456 80

11412 75

23678 75

14567 75

12345 75

24567 70

22456 70

12245 70

===================

Tests graded = 15

===================

Score Frequency

===================

100 1

95 1

85 3

80 3

75 4

70 3

===================

Class Average = 80

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