MultiLinkedlist.cpp

//PROGRAM FOR COURSE REGISTRATION 
//function prototypes
void AddCourse(); //done
void DeleteCourse(); //done
void SearchCourse(); //done
void PrintCourse(); //done
void AddStudent(); //done
void DeleteAllStudents(); //used in deletecourse to delete all students before deleting a course
void DeleteStudentfromCourse(); //done
void DeleteStudentCompletely();
void SearchStudent();
void FullSearchStudent();
void PrintStudent();

#include<iostream>
using namespace std;

 //structs defined 
struct Student //list of students 
{
	string Name;
	string Seatno; //seat number of student like b23001
	Student* nextstudent; //pointer for next student in list 
};

struct Course //course list 
{ 
	string CourseNo; //the course number like cs-451
	string CourseName;
	Student* Studentlist; //list of the students which will be attached to each course(nested list)
	Course* nextcourse; //pointer to next course 
};

Course* coursehead = NULL; //global initial pointer to course which is now empty

//function implementation
void AddCourse()
{
    Course* course = new Course();
	
	string coursenumber, coursename;
	cout<< "Enter the course number:\t";
	cin>> coursenumber;
	cout<< "Enter the course name:\t";
	cin>> coursename;
	course->CourseNo = coursenumber;
	course->CourseName = coursename;
	course->Studentlist = NULL;
	course->nextcourse= NULL; //initially the next course is null
	
	if(coursehead==NULL) //if the course list is empty then assign the first added course as head
	{
		coursehead = course;
	}
	else
	{
		Course* temp= coursehead;
		while(temp->nextcourse!=NULL)
		{
			temp=temp->nextcourse; //traverse till end
		}
		temp->nextcourse=course; //place the newly added course to the end
	}
	cout<< "course added successfully!" <<endl;
}

void DeleteAllStudents(Student* studentlist) //WHILE REVISING CHECK HERE WHY ENTIRE STUDENTLIST IS PASSED?
{
    Student* temp;
    while (studentlist != NULL) 
    {
        temp = studentlist; //save the first node or the headnode of the student list
        studentlist = studentlist->nextstudent; //traverse karte jao agey barhte jao
        delete temp; // ek ek student ko delete krte jao
    }
}

void DeleteCourse()
{
	string input; //deletion condiion will work on either of the two if the name or number is entered then delete that specific course
	cout<< "Enter the COURSE NAME or COURSE NUMBER to delete:\t";
	cin.ignore();
	getline(cin,input);
	

	//if there us one course then delete it
	Course* temp = coursehead;
	Course* prev = NULL;
	
	 if(temp==NULL) //if there is no course
	{
		cout<< "No course to delete!" << endl;
		return;
	}
	//if the course to be deleted is the first node(head)
	if(temp->CourseName == input || temp->CourseNo== input)
	{
		coursehead= temp->nextcourse; //update the coursehead to next course before deleteing it to avoid losing the entire list
		DeleteAllStudents(temp->Studentlist); //delete all students before deleting teh course bcx if course doesnt exist the student should also not be registered to it
		delete temp;
		cout<< "Course list is now empty after deletion" << endl;
		return;
	}
	//if there is a certain course then first search it and then delete it
	while (temp->CourseName != input && temp->CourseNo!= input && temp!=NULL) { //traverse the list and search
        prev = temp; //keep saving current nodes while moving forward (Because we move first, so we must save prev before losing reference.)
		temp=temp->nextcourse;
	}
    
	//case: if course found somewhere in list
	prev->nextcourse= temp->nextcourse; //skip the node to delete and link the prev node to the next node of the one to be deleted 
	DeleteAllStudents(temp->Studentlist);
	delete temp; 
	cout<< "Course deleted succesfully!";
	
}

void SearchCourse() //to search and display a specific course
{
	 string input;
	 cout<< "Enter the COURSE NAME or COURSE NUMBER to search:\t";
	 cin.ignore();
	 getline(cin,input);
	 
	 Course* temp = coursehead; //assign the first headnode course to temp for traversal
	 bool found = false;
	 while(temp!=NULL) //traverse till end
	{
	 	if((temp->CourseName==input) || (temp->CourseNo==input))
	 	{
	 			cout<< "Course  " << temp->CourseName << " (" << temp->CourseNo << ") found in the courses list!" << endl;
	 			found = true;
		 }
	 temp=temp->nextcourse; //keep traversing
}
    if(!found){
	cout<< "Course not found in the list!" << endl;
}
}

void PrintCourse()
{
	cout<< "***LIST OF COURSES***" << endl;
	Course* temp = coursehead;
	while(temp!=NULL)
	{
		cout << temp->CourseName << " (" << temp->CourseNo << ")"<< endl;
		temp=temp->nextcourse;
	}
	
}
	
void AddStudent()
{
    Student* student = new Student();
	
	string name, seatnumber , inputcourse;
	cout<< "Enter the name of the student:\t";
	cin>> name;
	cout<< "Enter the seat number of the student:\t";
	cin>> seatnumber;
	cout<< "Which course name or number to register with ?:\t";
	cin>> inputcourse;
	
	//searching for code
	Course* coursetemp = coursehead;
	while(coursetemp!=NULL)
	{
		if((coursetemp->CourseName== inputcourse ) || (coursetemp->CourseNo== inputcourse))
		{
			break; //course found
		}
		coursetemp=coursetemp->nextcourse;
	}
	
	//if code does not exist then return and delete the student 
	if(coursetemp==NULL)
	{
		cout << "Course does not exist : Cannot register student" << endl;
		delete student; //delete the student to free the memory bcz course doesnt exist then a student cannot be registered
		return;
	}
	
	student->Name = name;
	student->Seatno = seatnumber;
	student->nextstudent= NULL; //initially next student is null
	
	
		if(coursetemp->Studentlist==NULL) //if the student list is empty then assign the first added student as head
	{
		coursetemp->Studentlist = student;
	}
	else
	{
		Student* temp= coursetemp->Studentlist; //studentlist of that particular course where student is being added (a pointer to the head of the student list in that course)
		while(temp->nextstudent!=NULL)
		{
			temp=temp->nextstudent; //traverse till end
		}
		temp->nextstudent=student; //place the newly added student to the end
	}
	cout<< name << " " << seatnumber << " registered to the course " << coursetemp->CourseName <<endl;
	
}

void DeleteStudentfromCourse()
{
	string inputstudent;
	cout<< "Enter the NAME or SEAT NUMBER of the student to delete:\t";
	cin.ignore();
	getline(cin,inputstudent);
	
	string inputcourse;
	cout<< "Enter the COURSE NAME or COURSE NUMBER to delete:\t";
	cin.ignore();
	getline(cin,inputcourse);
	
	Course* coursetemp = coursehead;
	

	//find the course
	while(coursetemp!=NULL) //keep traversing until u find that particular course
	{
		if((coursetemp->CourseName== inputcourse ) || (coursetemp->CourseNo== inputcourse))
		{
			break; //course found
		}
		coursetemp=coursetemp->nextcourse; //to move forward
	}
	
	if (coursetemp == NULL)  //if the course was not found then return
    {
        cout << "Course not found.\n";
        return;
    }
	// find the student inside the course
	Student* studenttemp= coursetemp->Studentlist;
	Student* prev= NULL;
	while(studenttemp!=NULL) //keep traversing until u find the student
	{
		if((studenttemp->Name == inputstudent) || (studenttemp->Seatno==inputstudent))
		{
		if (prev==NULL) //if the student to be deleted is the first in the list then 
		{
		   coursetemp->Studentlist = studenttemp->nextstudent;	//update the head node of student list by the next student in list of that course
		}
		 else
		 {
		 	 prev->nextstudent= studenttemp->nextstudent; //otherwise link prev student to next
		 }
	 	cout<< studenttemp->Name << " (" << studenttemp->Seatno << ") deleted from course " << coursetemp->CourseName << endl;
	 	delete studenttemp; //and then delete that particular inputted student
	    return;
	 		 
		 }
		 prev = studenttemp; //move the prev to current student (Because we check first, then move forward.)
		 studenttemp= studenttemp->nextstudent; //keep moving the student list
	}
	cout << "Student not found in the list!" << endl;		 
}

void DeleteStudentCompletely()
{
    string inputstudent;
    cout << "Enter the NAME or SEAT NUMBER of the student to delete:\t";
    cin.ignore();
    getline(cin, inputstudent);

    Course* coursetemp = coursehead; // Start from first course

    bool found = false; // To check if student was deleted from any course

    while (coursetemp != NULL) // Traverse all courses
    {
        Student* studenttemp = coursetemp->Studentlist;
        Student* prev = NULL;

        while (studenttemp != NULL) // Traverse students in the course
        {
            if ((studenttemp->Name == inputstudent) || (studenttemp->Seatno == inputstudent))
            {
                if (prev == NULL) // If first student in the course
                {
                    coursetemp->Studentlist = studenttemp->nextstudent; //update the head node of student list by the next student in list of that course
                }
                else
                {
                    prev->nextstudent = studenttemp->nextstudent; //link the prev student with the next student and skip the one being deleted
                }

                cout << studenttemp->Name << " (" << studenttemp->Seatno << ") removed from " << coursetemp->CourseName << endl;
                delete studenttemp;
                found = true;
                break; // Exit loop as deletion is done for this course
            }

            prev = studenttemp; //save current student in prev first check and then move forward
            studenttemp = studenttemp->nextstudent; //keep movinf forward
        }

        coursetemp = coursetemp->nextcourse; // Move to next course for traversing all courses in the list
    }

    if (!found)
    {
        cout << "Student not found in any course!" << endl;
    }
    else
    {
        cout << "Student completely removed from all courses." << endl;
    }
}

void SearchStudent() {
    string inputcourse, inputstudent;
    
    cout << "Enter the COURSE NAME or COURSE NUMBER: ";
    cin.ignore();
    getline(cin, inputcourse);

    cout << "Enter the STUDENT NAME or SEAT NUMBER: ";
    getline(cin, inputstudent);

    Course* coursetemp = coursehead;

    // Search for the course
    while (coursetemp != NULL) {
        if (coursetemp->CourseName == inputcourse || coursetemp->CourseNo == inputcourse) {
            break; // Course found
        }
        coursetemp = coursetemp->nextcourse;
    }

    if (coursetemp == NULL) {
        cout << "Course not found!\n";
        return;
    }

    // Search for the student in the course's student list
    Student* studenttemp = coursetemp->Studentlist; //point to the first student head in the specific course
    while (studenttemp != NULL) 
	{
        if (studenttemp->Name == inputstudent || studenttemp->Seatno == inputstudent) {
            cout << "Student " << studenttemp->Name << " (" << studenttemp->Seatno << ") is enrolled in " << coursetemp->CourseName << ".\n";
            return;
        }
        studenttemp = studenttemp->nextstudent;
    }

    cout << "Student not found in this course!\n";
}


void FullSearchStudent() {
    string inputstudent;

    cout << "Enter the STUDENT NAME or SEAT NUMBER: ";
    cin.ignore();
    getline(cin, inputstudent);

    Course* coursetemp = coursehead;
    bool found = false;  //to track the student in courses

    while (coursetemp != NULL) { //for each course check tthe student list inside this
        Student* studenttemp = coursetemp->Studentlist;

        while (studenttemp != NULL) { //traverse untill teh entire studentlist for that particular course
            if (studenttemp->Name == inputstudent || studenttemp->Seatno == inputstudent) {
                cout << "Student " << studenttemp->Name << " (" << studenttemp->Seatno << ") is enrolled in " << coursetemp->CourseName << ".\n";
                found = true;
            }
            studenttemp = studenttemp->nextstudent; //keep student list moving forward
        }
        coursetemp = coursetemp->nextcourse; //keep courses moving forward
    }

    if (!found) {
        cout << "Student not found in any course!\n";
    }
}

void PrintStudentInCourse() { //this prints all students in a course
    string inputcourse;
    
    cout << "Enter the COURSE NAME or COURSE NUMBER: ";
    cin.ignore();
    getline(cin, inputcourse);

    Course* coursetemp = coursehead;

    // Search for the course
    while (coursetemp != NULL) {
        if (coursetemp->CourseName == inputcourse || coursetemp->CourseNo == inputcourse) {
            break; // Course found
        }
        coursetemp = coursetemp->nextcourse;
    }

    if (coursetemp == NULL) {
        cout << "Course not found!\n";
        return;
    }

    // Print students in the course
    Student* studenttemp = coursetemp->Studentlist;
    if (studenttemp == NULL) { //if the studentlist is empty
        cout << "No students enrolled in this course!\n";
        return;
    }

    cout << "Students enrolled in " << coursetemp->CourseName << ":\n";
    while (studenttemp != NULL) { //traverse the list and print the student name and seatno
        cout << "- " << studenttemp->Name << " (" << studenttemp->Seatno << ")\n";
        studenttemp = studenttemp->nextstudent;
    }
}


int main()
{
	cout<< "WELCOME TO THE COURSE REGISTRATION PROGRAM:\t";
	int option;
	do
	{
    cout << "\n1) Add a course\n"
         << "2) Delete a course\n"
         << "3) Search a course\n"
         << "4) Print all courses\n"
         << "5) Add a student to a course\n"
         << "6) Delete a student from a course\n"
         << "7) Delete a Student's Data Completely\n"
         << "8) Search a student\n"
         << "9) Search a student in all courses\n "
         << "10) Print all students in a course\n"
         << "11) Exit the program" << endl;
	cout<< "\nChoose the action you want to perform:\n";
	cin>> option;
	switch(option)
	{
		case 1: //add a course
	    AddCourse();
		break;
		
		case 2: //delete a course
		DeleteCourse();
		break;
		
		case 3: //search a course
		SearchCourse();
		break;
			
		case 4: //print all courses
		PrintCourse();
		break;
		
		case 5: //Add a student to a course
		AddStudent();
		break;
		
		case 6: //delete a student from a course
		DeleteStudentfromCourse();
		break;
		
		case 7: //delete a student( complete removal of data)
		DeleteStudentCompletely();
		break;
		
		case 8: //search a student
		SearchStudent();
		break;
		
		case 9: //search a student everywhere(in all courses enrolled)
		FullSearchStudent();
		break;
		
		case 10: //print students in a course
		PrintStudentInCourse();
		break;
		
		case 11: //exit the program
		cout << "Program exited!" << endl;
		break;
		
		default: //invalid option entered 
		cout << "Invalid option! please enter a valid option" << endl;
	} 
	}while(option!=11);

	return 0;
}