Question

C++

Write a program that asks a teacher to input a student’s first name, last name, and four test scores. The program should find the average of the four test scores and should then write the following information to a file named “students.txt”

last_name

first_name

average

A student's first name of “XX” should be used as a sentinel value and no numeric grades less than 0 or greater than 100 should be accepted.  The program should then read the information in for the file “students.txt”, and for each student display the following on the monitor:

first_name last_name    average

first_name last_name    average

…

Number of students        n

Overall average:               nn.n

Note: all averages should be displayed with one decimal position

Answer 1

Below is the source code. Please comment if any queries or issues. Thanks.

#include <iostream>
#include<bits/stdc++.h> 
#include <fstream>
using namespace std;


class Student{
    public:
    string firstName;
    string lastName;
    float marks[4];
    float average;
};
int main()
{
    char cont = 'N';
        float exam1[100], total = 0 , total_average = 0;
    int count=0;
    ifstream infile; 
    string line;
        
    do {
        
        Student s;
        cout<<"Enter Student's first name"<<endl;
        cin>>s.firstName;
        cout<<"Enter Student's Last Name" <<endl;
        cin>>s.lastName;
        cout<<"Enter Marks"<<endl;
        float marks;
        for (int i = 0; i < 4 ; i++){
            cin>>marks;
            if (marks <0 || marks > 100){
                cout<<"Marks cannot be less than 0 or greater than 100, please enter again"<<endl;
                i = i-1;
                continue;
            }
            else
                s.marks[i] = marks;
        }
        
        
        float sum = 0;
        for (int i = 0; i < 4; i++){
            sum = sum + s.marks[i];
        }
        s.average = sum/4;

        char filename[ ] = "students.txt";

        ofstream outputfile;


        // creating, opening and writing/appending data to a file
        
        outputfile.open(filename, ios::out|ios::app);

        // simple error handling for file creating/opening for writing, test if fail to open the file
        
        if(outputfile.fail())
        {
            cout<<"The "<<filename<<" file could not be created/opened!\n";
            exit(1); // just exit
        }
        else
        {
            cout<<"The "<<filename<<" file was created and opened successfully!\n";
           // outputfile<<"Writing some data to this file\n";
            //outputfile<<"------------------------------\n";
            cout<<"Check the "<<filename<<" file contents :-)"<<endl;
            cout<<"If the file already have had data, the new data will be appended\n";
            
            outputfile<<s.firstName<<" "<<s.lastName<< " " << fixed << setprecision(1) << s.average;
            
            outputfile<<endl;
            
            outputfile.close();
        
            if(outputfile.fail())
            
            {
                cout<<"The "<<filename<<" file could not be closed!\n";
                exit(1);
            }
            // test if successful to close the file, do the following...
            else
                cout<<"\nThe "<<filename<<" file was closed successfully!\n";
        }
        cout<<"Enter Y/y if there is another student"<<endl;
        
        cin>>cont;
    }while(cont == 'Y' || cont == 'y');

  ifstream myfile ("students.txt");
  if (myfile.is_open())
  {
    
    while ( getline (myfile,line) )
    {
      cout << line << '\n';
    }
    myfile.close();
  }

  else cout << "Unable to open file";
  
  
  //To calcualte the average 
     cout<< "Displaying the Student Data\n";
     infile.open("students.txt");// file containing numbers in 3 columns 
     if(infile.fail()) // checks to see if file opended 
     { 
      cout << "error" << endl; 
      return 1; // no point continuing if the file didn't open...
     } 
     while(getline(infile, line)) // reads file to end of *file*, not line
     { 
         
         stringstream ss(line);
         char a[50], b[50]; 
         float c;
        if (ss >> a >> b >> c)
        {
            exam1[count] = c;
            count++;
        }
      } 
    infile.close(); 
    cout << "Number of students " << count <<"\n";
   for (int i=0; i<count;i++){
       total = total + exam1[i];
   }
   total_average = total/count;
   cout << "Overall average: "  << fixed << setprecision(1) << total_average; 

  return 0;

}

Below is the execution screenshot