Question

: Files and Exceptions: Write a program to create and use a grade book for a course. The gradebook is created as a file named as “Course_Name.dat” and includes the following information about students: Student ID, First Name, Last Name, and Grade. Assume the following structure for the gradebook file:1.Students’ records are separated by a new-line character.2.No field includes any white-space character, and fields are separated by space.3.The order of the fields is the same for all the records.Based on the above explanation, write a program that shows a menu including the following options to the user, and responds according to the user selection.Press 1 to create a new gradebook file. Press 2 to search a student in an existing gradebook file. Press 3 to add a student record. If the user selects 1, he/she is asked for the gradebook file name and a new file is created. In case the file already exists, user can choose to keep it or delete all the contents of the existing file.If the user selects 2, he/she is asked for the file name and in case the file name exists, he/she can enter a student ID to search. In case the file doesn’t exist, the program throws an exception.If the user selects 3, he/she is asked for the file name and in case the file already exists, the information of the student is read from the keyboard and the student record is appended to the file. In case the file doesn’t exist, the program throws an exception.

IN C++ WITH MICROSOFT VISUAL STUDIO 2017 IF POSSIBLE PLEASE

Answer 1

#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>

using namespace std;

// This is helper function to spilt a line by whitespaces
vector<string> spilt(const string &line){
    
    string buf; // Just a temp buffer
    stringstream ss(line); // String stream

    vector<string> tokens; // Array/Vector of words

    while (ss >> buf)
        tokens.push_back(buf); // Add each word in array

    return tokens;
}

// This is helper function to show menu to user
void show_menu(){
    
    cout << "\n\n";
    cout << "1. Create new Gradebook file\n";
    cout << "2. Search a student in existing record\n";
    cout << "3. Add a student record\n";
    cout << "4. Exit\n";
    cout << "Please select one choice\n";
}


// This function is to create new book
void create_new_book(){
    
    string filename;
    cout << "Enter a file name\n";
    cin >> filename;
    
    ofstream file(filename,std::ios_base::app);
    if(!file)
    {
        // Throw Exception if file could not be opened
        throw runtime_error("Could not open file");
    }
    file.close();
}

// This function is to seach student id in the book
void search_book(){
    
    string filename;
    cout << "Enter a file name\n";
    cin >> filename;
    
    ifstream file(filename);
    if(!file)
    {
        // Throw Exception if file does not exists
        throw runtime_error("Could not open file");
    }
    
    string search_param; // Student ID which needs to be searched
    cout << "Enter Student ID to search\n";
    cin >> search_param;

    string line;
    // Read file line by line
    while (getline( file, line ))
    {
        // Create a array/vector of words from single line
        vector<string> words = spilt(line);
        
        // word[1] (2nd positon is the student id value. Array starts with 0, so word[1])
        // check is given student id matches the student id in current line
        if(search_param == words[1]){
            // Print the whole line
            cout << line;
            break;
        }
    }
    file.close();
}

// This function is to add new record to existing file
void add_record(){
    
    string filename;
    cout << "Enter a file name\n";
    cin >> filename;
    
    ofstream file(filename, std::ios_base::app);
    if(!file)
    {
        // Throw Exception if file does not exists
        throw runtime_error("Could not open file");
    }
    
    string student_id, first_name, last_name, grade;
    cout << "Enter Student ID, First Name, Last Name, Grade\n";
    cin >> student_id >> first_name >> last_name >> grade;
    
    // Add the contents to the file
    file << "Student_ID " << student_id << " First_name " << first_name << " Last_name " << last_name << " Grade " << grade << endl;
    file.close();
}

// This is main function
int main() {
    
    // variable which keep hold of the option selected
    int option = 0;
    do {
        show_menu();
        cin >> option;
        
        switch (option){
            case 1:
                create_new_book();
                break;
            case 2:
                search_book();
                break;
            case 3:
                add_record();
                break;
            case 4:
                break;
            default:
                cout << "You entered a wrong option\n";
        }
    }while (option != 4);
   return 0;
}