honoreWork.cpp

#include <iostream>
#include <fstream>
#include <vector>
#include <sstream>
#include <type_traits>
using namespace std;
struct Student
{
	string studentName;
	int age;
	int rollNumber;
	float marks;
};
void merge(vector<Student> &arr, int l, int m, int r)
{
	int i, j, k;
	int n1 = m - l + 1;
	int n2 = r - m;
	vector<Student> L, R;
	for (i = 0; i < n1; i++)
		L.push_back(arr[l + i]);
	for (j = 0; j < n2; j++)
		R.push_back(arr[m + 1 + j]);
	i = 0;
	j = 0;
	k = l;
	while (i < n1 && j < n2)
	{
		if (L[i].marks >= R[j].marks)
		{
			arr[k] = L[i];
			i++;
		}
		else
		{
			arr[k].marks = R[j].marks;
			j++;
		}
		k++;
	}
	while (i < n1)
	{
		arr[k] = L[i];
		i++;
		k++;
	}
	while (j < n2)
	{
		arr[k] = R[j];
		j++;
		k++;
	}
}
void mergeSort(vector<Student> &arr, int l, int r)
{
	if (l < r)
	{
		int m = l + (r - l) / 2;
		mergeSort(arr, l, m);
		mergeSort(arr, m + 1, r);
		merge(arr, l, m, r);
	}
}
void getStudent(string fileName)
{
	cout << "================Register Students====================" << endl;
	cout << endl;

	ofstream file1;
	file1.open(fileName, ios::out | ios::app);
	Student student;
	if (file1.is_open())
	{
		cout << "Enter the student name" << endl;
		getline(cin, student.studentName);
		file1 << student.studentName << ",";
		cout << "Enter the student age" << endl;
		cin >> student.age;
		if (student.age > 30 || student.age < 10)
		{
			cout << "Not eligible should be between 10 and 30 years" << endl;
			exit(0);
		}
		file1 << student.age << ",";
		cout << "Enter the student roll number" << endl;
		cin >> student.rollNumber;
		if (!cin.fail())
		{
			if (student.rollNumber > 0)
			{
				file1 << student.rollNumber << ",";
				cout << "Enter the student marks" << endl;
			}
			else
			{
				cout << "RE enter the roll number it's invalid" << endl;
				cin.clear();
				cin.ignore(256, '\n');
				cin >> student.rollNumber;
				cin.ignore(256, '\n');
			}
		}
		else
		{
			cout << "RE enter the roll number it's invalid" << endl;
			cin.clear();
			cin.ignore(256, '\n');
			cin >> student.rollNumber;
			cin.ignore(256, '\n');
		}
		cin >> student.marks;
		if (student.marks < 0 || student.marks > 50)
		{
			cout << "Invalid marks try again" << endl;
			cin >> student.marks;
		}
		file1 << student.marks << endl;
		file1.close();
	}
	else
	{
		cout << "Couldn't open file" << endl;
	}
}
void display(string fileName)
{
	cout << endl;
	cout << endl;
	cout << "================Students====================" << endl;
	cout << endl;
	ifstream file;
	file.open(fileName, ios::in);
	string line;
	vector<Student> students;
	cout << "Studentname"
		 << "\t"
		 << "age"
		 << "\t"
		 << "roll"
		 << "\t"
		 << "marks" << endl;
	cout << endl;
	if (file.is_open())
	{
		string field1, field2, field3;

		while (getline(file, line))
		{
			Student student;
			stringstream ss(line);
			getline(ss, student.studentName, ',');
			getline(ss, field1, ',');
			getline(ss, field2, ',');
			getline(ss, field3, ',');
			student.age = stoi(field1);
			student.rollNumber = stoi(field2);
			student.marks = stof(field3);
			students.push_back(student);
		}
		file.close();
	}
	cout << "Length: " << students.size() - 1;
	mergeSort(students, 0, students.size() - 1);
	for (int i = 0; i < students.size(); i++)
	{
		cout << students[i].studentName + "\t"
			 << "\t" << students[i].age << "\t" << students[i].rollNumber << "\t" << students[i].marks << endl;
	}
}
int main()
{
	ofstream file;
	int choice;
	cout << "============Welcome==================" << endl;
	cout << endl;
	cout << "Choose in the following" << endl;
	cout << endl;
	cout << "1.Register Student" << endl;
	cout << "2.View all Students" << endl;
	cout << "Enter choice" << endl;
	cin >> choice;
	cin.ignore();

	switch (choice)
	{
	case 1:
		getStudent("export.txt");
		break;
	case 2:
		display("export.txt");
		break;
	default:
		cout << "Invalid choice try again" << endl;
	}

	return 0;
}