It works!!!!

todx.cpp

#include <iostream.h>
#include <string.h>
#include <ctype.h>
#include <fstream.h>

// Classes

class Todo{
  public:
    char content[200];
    char status;
    int _index;
};

class List {
  public:
    Todo list[20];

    char title[100];
    char tags[10][20];

    int _listIndex;     // Variable to count the filling of list
    int _tagIndex;      // Variable to count the filling of tags
    int _hasTags;

    List();                 // Asks for #title(required) and #tags(can be skipped).

    List(char Title[100]);  // Initialize the #list with #title

    void enter();           // Enter the info given by user

    void addTag(char Tag[20]); // Add the tag to Tags

    void setTitle(char Title[100]); // Set the Title given

    void view();            // View the list's #title #tags and #content

    void indexView();       // View the contents with the index

    void tagView();         // View only Title and tags

    void todoView(int);     // View the todo of index passed

    void tagIndexView();    // View the Title and Tags with the index

    void append();          // append a new ToDo in the #list

    void removeTodo(int);   // delete the list at index passed

    void removeTag(int);   // delete the tag at index passed

    void changeStatus(int index, char status); // Changes Status of the Item of #index to #status

    ~List() {}
};
List::List(){
    _listIndex = 0;
    _tagIndex = 0;
    _hasTags = 0;
}

List::List(char Title[100]) {
    _listIndex = 0;
    _tagIndex = 0;
    _hasTags = 0;

    strcpy(title, Title);
}

void List::enter(){
    cout << "Enter title for your list" << endl << " +> " ;
    cin.getline(title, sizeof(title));

    char choice[10];
    cout << "Do you want some tags? (yes/no)" << endl << " ?> " ;
    cin.getline(choice, sizeof(choice));

    if (!(strcmp(choice, "yes")*strcmp(choice, "y"))) {
        char tagTemp[20];

        cout << "Enter the tag one at a time" << endl << "\'d\' when done " << endl;
        cout << " +> " ;

        while (1) {
            cin.getline(tagTemp, sizeof(tagTemp));

            if (strcmp(tagTemp, "d") != 0) {
                addTag(tagTemp);
                cout << " +> " ;
            }

            else {
                break;
            }
        }

        _hasTags = 1;
    }

    // cout << "Has tags = " << _hasTags << endl;

}


void List::addTag(char Tag[20]) {
    strcpy(tags[_tagIndex++], Tag);
}

void List::setTitle(char Title[100]) {
    strcpy(title, Title);
}


void List::view() {
    cout << title << endl;
    cout << "============" << endl;

    if (_hasTags) {
        cout << "Tags : ";
        for (int i = 0; i < _tagIndex; i++) {
            cout << tags[i] << " ";
        }

        cout << endl << endl;
    }

    for (int i = 0; i < _listIndex; i++) {
        cout << "  [" << list[i].status << "]  ";
        cout << list[i].content << endl;
    }
}

void List::indexView() {
    cout << title << endl;
    cout << "============" << endl;

    if (_hasTags) {
        cout << "Tags : ";
        for (int i = 0; i < _tagIndex; i++) {
            cout << tags[i] << " ";
        }

        cout << endl << endl;
    }

    for (int i = 0; i < _listIndex; i++) {
        cout << " " << i << ". [" << list[i].status << "]  ";
        cout << list[i].content << endl;
    }
}

void List::tagView() {
    cout << title << endl;

    if (_hasTags) {
        cout << "Tags : ";
        for (int i = 0; i < _tagIndex; i++) {
            cout << tags[i] << " ";
        }

        cout << endl;
    }

}

void List::todoView(int index) {
    cout << index << ".  [" << list[index].status << "]  ";
    cout << list[index].content << endl;
}

void List::tagIndexView() {
    cout << title << endl;
    cout << "============" << endl;

    if (_hasTags) {
        cout << "Tags : ";
        for (int i = 0; i < _tagIndex; i++) {
            cout << tags[i] << " ";
        }

        cout << endl << endl;
    }

    else {
        cout << "No tags here." << endl;
    }
}

void List::append(){
    char Content[200];
    cout << "Enter the content of ToDo" << endl << " +> ";
    cin.getline(Content, sizeof(Content));

    strcpy(list[_listIndex].content, Content);

    list[_listIndex].status = ' ';
    list[_listIndex]._index = _listIndex;
    _listIndex++;
}

void List::removeTodo(int index) {
    for (int i = index; i < _listIndex; i++) {
        list[i] = list[i + 1];
    }
    _listIndex--;
}

void List::removeTag(int index) {
    for (int i = index; i < _tagIndex; i++) {
        strcpy(tags[i], tags[i + 1]);
    }
    _tagIndex--;
    if (_tagIndex == 0) {
        _hasTags = 0;
    }
}

void List::changeStatus(int index, char status){
    list[index].status = status;
}

void search(char term[], List arrayL[6]){
    int len = strlen(term);
    int found = 0;

    // Search in titles

	for (int i = 0; i < 6 ; i++) {
		int z = 0;
		found = 0;

		for (unsigned int k = 0; k < strlen(arrayL[i].title); k++) {
			if (tolower(term[z++]) == tolower(arrayL[i].title[k])) {
				found = 1;
				// cout << "Found title" << endl;
			}

			else {
				found = 0;
				z = 0;
			}

			if (z == len) {
				if (found) {
					break;
				}
				z = 0;
			}
		}

		if (found) {
			cout << "Found in title, Index => " << i << endl << arrayL[i].title << endl;
		}
	}

	// Search in Tags

	for (int io = 0; io < 6 ; io++) {
		int z = 0;
		found = 0;
		for (int k = 0; k < arrayL[io]._tagIndex; k++) {
			z = 0;

			for (unsigned int c = 0; c < strlen(arrayL[io].tags[k]); c++) {

				if (tolower(term[z++]) == tolower(arrayL[io].tags[k][c])) {
					found = 1;
				}

				else {
					found = 0;
					z = 0;
				}

				if (z == len) {

					if (found) {
						break;
					}

					z = 0;
				}
			}

			if (found) {
				cout << "Found in tag, Index => " << io << endl;
				arrayL[io].tagView();

				break;
			}
		}
	}

	// Search in Todos

	for (int iz = 0; iz < 6 ; iz++) {
		int z = 0;
		found = 0;
		for (int k = 0; k < arrayL[iz]._listIndex; k++) {
			z = 0;
			for (unsigned int c = 0; c < strlen(arrayL[iz].list[k].content); c++) {

				if (tolower(term[z++]) == tolower(arrayL[iz].list[k].content[c])) {
					found = 1;
				}

				else {
					found = 0;
					z = 0;
				}

				if (z == len) {

					if (found) {
						break;
					}

					z = 0;
				}
			}

			if (found) {
				cout << "Found in ToDo, List Index => " << iz << endl;

				arrayL[i].view();

				break;
			}
		}
	}
}
void Export(List Array[6], int _arrayLindex){
	char fname[40];

	cout << "Enter the Export file name " << endl  << " +> " ;
	cin.getline(fname, sizeof(fname));

	strcat(fname, ".tdexp");

	ofstream file;
	file.open(fname);

	for (int itt = 0; itt < _arrayLindex; itt++) {
		file << Array[itt].title << endl;
		file << "===============" << endl;

		file << "Tags : ";
		for (int j = 0; j < Array[itt]._tagIndex; j++) {
			file << Array[itt].tags[j] << " ";
		}
		file << endl;

		for (int k = 0; k < Array[itt]._listIndex; k++) {
			file << " [" << Array[itt].list[k].status << "] ";
			file << Array[itt].list[k].content << endl;
		}

		file << endl;
	}

	cout << "File exported to : " << fname << " successfully :)" << endl;

	file.close();
}

List arrayL[6];
List currentL;

int _arrayLindex = 0;
int _currentLindex;
int isOpenL = 0; // For checking wether a list is open or not

char filename[20] = "data.tdx";

// Fxns Used

void    initiate();         // Initiate the data before user inteface
int     parse(char []);     // run the command entered by the users
void    stats();           // display stats of opened list
void    openL(int);         // open the list specified by index
void    displayL();         // display all the lists
int     confirm();          // ask for confirmation (y/n)
void    empty();            // remove data from the program & data-file
void    finish();           // save the data to the data-file

void initiate() {
	// Fxn to read data from external file int the array of Lists
	fstream file(filename, ios::in|ios::binary);
	List tempOb; // temperary object

	while (file.read((char*)&tempOb, sizeof(tempOb))) {
		arrayL[_arrayLindex++] = tempOb;
	}

	file.close();
}

int parse(char command[80]){
	// Fxn to Parse(execute) the command passed
	/// Here a crazy fun expression is used in if () {} to compare strings
	/// Since we wanted any of them to be zero, hence, they were multiplied
	/// to give zero. Mathematically it is quite accurate and syntactically
	/// beautiful.

	int success = 0; // to mark wether a command completed successfully

	if (!(strcmp(command, "new") * strcmp(command, "n"))) {
		// Create a new List
		arrayL[_arrayLindex++].enter();
		success = 1;
	}

	else if (!(strcmp(command, "stats") * strcmp(command, "stat"))) {
		// Display the stats
		stats();
		success = 1;
	}

	else if (!(strcmp(command, "open") * strcmp(command, "o"))) {
		// Open existing lists
		if (_arrayLindex) {
			if (isOpenL) {
				arrayL[_currentLindex] = currentL;
				finish();
			}

			int choice;
			cout << "Enter The No. of List to be opened" << endl;

			displayL();

			cout << " #> " ;
			cin >> choice;
			cin.ignore();

			while ( !(0 <= choice && choice < _arrayLindex) ) {
				cout << "Invalid choice choose again" << endl;
				cout << " #> " ;
				cin >> choice;
				cin.ignore();
			}

			openL(choice);

			isOpenL = 1;
		}

		else {
			cout << "No List found, create a new one with \'n\' or \'new\'" << endl;
		}

		success = 1;
	}

	else if (!(strcmp(command, "append") * strcmp(command, "a"))) {
		// Append a new Todo to the currently opened list
		if (isOpenL) {
			currentL.append();
		}

		else {
			cout << "No List is opened, Open a list first" << endl;
		}
		success = 1;
	}

	else if (!(strcmp(command, "mark") * strcmp(command, "m"))) {
		// Mark/(change status) a Todo with a given charater
		if (isOpenL) {
			int choice;
			currentL.indexView();

			cout << "Choose the Todo to mark : " << endl << " #> ";
			cin >> choice;

			while (choice >= currentL._listIndex || choice < 0) {
				cout << "Invalid Choice Try again" << endl << " #> ";
				cin >> choice;
			}

			char status;

			cout << "Enter The new Status" << endl << " +> " ;
			cin >> status;
			cin.ignore();

			currentL.changeStatus(choice, status);
		}

		else {
			cout << "No List is opened, Open a list first" << endl;
		}

		success = 1;
	}

	else if (!(strcmp(command, "addtag") * strcmp(command, "addt"))) {
		// Append a new Todo to the currently opened list
		if (isOpenL) {
			char newTag[40];

			cout << "Enter the New Tag " << endl << " +> ";
			cin.getline(newTag, sizeof(newTag));
			currentL.addTag(newTag);
		}

		else {
			cout << "No List is opened, Open a list first" << endl;
		}

		success = 1;
	}

	else if (!(strcmp(command, "view") * strcmp(command, "v"))) {
		// view todo's of the current list
		if (isOpenL) {
			currentL.view();
		}

		else {
			cout << "No List is opened, Open a list first" << endl;
		}

		success = 1;
	}

	else if (!(strcmp(command, "iview") * strcmp(command, "iv"))) {
		// view todo's of the current list with index
		if (isOpenL) {
			currentL.indexView();
		}

		else {
			cout << "No List is opened, Open a list first" << endl;
		}

		success = 1;
	}

	else if (!(strcmp(command, "search") * strcmp(command, "srch"))) {
		// Search the Database
		char searchTerm[40];

		cout << "Enter the search term " << endl << " +> ";
		cin.getline(searchTerm, sizeof(searchTerm));

		if (isOpenL) {
			arrayL[_currentLindex] = currentL;
		}

		search(searchTerm, arrayL);
		success = 1;
	}

	else if (!(strcmp(command, "save") * strcmp(command, "s"))) {
		// Save the data to the file
		if (isOpenL) {
			arrayL[_currentLindex] = currentL;
		}

		finish();
		success = 1;
	}

	else if (!(strcmp(command, "export") * strcmp(command, "exp"))) {
		// Export the data to a text file
		if (isOpenL) {
			arrayL[_currentLindex] = currentL;
		}

		Export(arrayL, _arrayLindex);

		success = 1;
	}

	else if (!(strcmp(command, "delete") * strcmp(command, "del"))) {
		// Delete Things

		char choice[10];
		cout << "What do you want to delete? (list/todo/tag)" << endl << " ?> ";
		cin.getline(choice, sizeof(choice));

		if (!(strcmp(choice, "list") * strcmp(choice, "List"))) {
			int index;

			cout << "Enter the Index of List to Delete " << endl;
			displayL();

			cout << " #> ";
			cin >> index;
			cin.ignore();
			cout << "Are you sure, This cannot be undone, This will delete the List ->" << endl;
			arrayL[index].view();

			if ( confirm() ) {
				for (int i = index; i < _arrayLindex - 1; i++) {
					arrayL[i] = arrayL[i+1];
				}
				_arrayLindex--;
			}
		}

		else if (!(strcmp(choice, "todo") * strcmp(choice, "Todo") * strcmp(choice, "ToDo"))) {

			if (isOpenL) {
				int index;

				cout << "Enter the Index of Todo to Delete " << endl;
				currentL.indexView();

				cout << " #> ";
				cin >> index;
				cin.ignore();
				cout << "Are you sure, This cannot be undone, This will delete the ToDo ->" << endl;
				currentL.todoView(index);

				if ( confirm() ) {
					currentL.removeTodo(index);
				}

				arrayL[_currentLindex] = currentL;  // To Help Improving Finalization
			}

			else {
				cout << "No List is opened, Open a list first" << endl;
			}
		}

		else if (!(strcmp(choice, "tag") * strcmp(choice, "tags") * strcmp(choice, "Tag"))) {

			if (isOpenL) {
				int index;

				cout << "Enter the Index of Tag to Delete " << endl;
				currentL.tagIndexView();

				cout << " #> " ;
				cin >> index;
				cin.ignore();
				cout << "Are you sure, This cannot be undone, This will delete the Tag ->" << endl;
				cout << currentL.tags[index] << endl;

				if ( confirm() ) {
					currentL.removeTag(index);
				}

				arrayL[_currentLindex] = currentL;  // To Help Improving Finalization
			}

			else {
				cout << "No List is opened, Open a list first" << endl;
			}
		}

		finish();
		success = 1;
	}

	else if (!(strcmp(command, "qdelete") * strcmp(command, "qdel"))) {
		// Delete Todo of current list using index
		/// qdelete -> Quick Delete

		if (isOpenL) {
			int index;

			cout << "Enter the Index of List to Delete " << endl;
			currentL.indexView();

			cout << " #> " ;
			cin >> index;
			cin.ignore();
			cout << "Are you sure, This cannot be undone, This will delete ->" << endl;
			currentL.todoView(index);

			if ( confirm() ) {
				currentL.removeTodo(index);
			}

			arrayL[_currentLindex] = currentL;
		}

		else {
			cout << "No List is opened, Open a list first" << endl;
		}

		finish();
		success = 1;
	}

	else if (!(strcmp(command, "clear") * strcmp(command, "clr"))) {
		// Refresh the data file
		// XXX WARN XXX -> Strictly, Not to be used By users, Deletes all Data

		if ( confirm() ) {
			ofstream file(filename, ios::trunc|ios::binary|ios::out);

			file.write("", sizeof(arrayL));
			file.close();

			empty();
			initiate();
		}

		success = 1;
	}

	else if (!(strcmp(command, "quit") * strcmp(command, "q"))) {
		// exit the program after saving it to the file

		if ( confirm() ) {
			if (isOpenL) {
				arrayL[_currentLindex] = currentL;
			}

			finish();
			success = -1;
		}

		else {
			success = 1;
		}
	}

	else if (!(strcmp(command, "help") * strcmp(command, "-h"))) {
		// View help
		char line[80];
		ifstream helpfile("help.txt");

		while (!helpfile.eof()) {
			helpfile.getline(line, sizeof(line));
			cout << line << endl;
		}

		helpfile.close();

		success = 1;
	}

	return success;
}

void stats(){
	// Display wether a list is open or not
	if (isOpenL) {
		cout << "This List is open : " << currentL.title << endl;
		cout << "Total No. of todos : " << currentL._listIndex << endl;
	}

	else {
		cout << "No list is open" << endl;
	}

	cout << "Total lists = " << _arrayLindex << endl;
}

void openL(int index) {
	currentL = arrayL[index];
	_currentLindex = index;

	cout << "Opened : " << currentL.title << endl;
	currentL.view();
}

void displayL() {
	for (int i = 0; i < _arrayLindex; i++) {
		cout << i << ". " << arrayL[i].title << endl;
	}
}

int confirm() {
	// can be used as if( confirm() ) /// Improves yes/no prompts
	char confm[10];
	cout << "Enter \'yes\' to continue" << endl << " ?> " ;
	cin.getline(confm, sizeof(confm));

	if (!(strcmp(confm, "yes") * strcmp(confm, "y"))) {
		return 1;
	}

	else{
		return 0;
	}
}

void empty() {
	List tarrayL[6];
	memcpy(arrayL, tarrayL, sizeof(arrayL));
	_arrayLindex = 0;
	isOpenL = 0;
}

void finish() {
	// Write the changes back to file
	ofstream file (filename, ios::out);
	for (int i = 0; i < _arrayLindex; i++) {
		file.write((char*)&arrayL[i], sizeof(arrayL[i]));
	}

	file.close();
}

int main() {
	initiate();

	cout << "=== --- --> TodX  <-- --- ===" << endl;
	cout << "Welcome to TodX the ultimate Todo list" << endl;
	cout << "v1.03a = Borland DOS build, docs at -> http://todx.rtfd.io" << endl;

	char command[80];

	while (1) {
		cout << "\n *> ";
		cin.getline(command, sizeof(command));

		if (!cin) {
			cout << "Have a Great Day :)" << endl;
			break;
		}

		int result = parse(command);

		if(result > 0){
			continue;
		}

		else if (result == 0) {
			cout << "Command not found, try `help` for help" << endl;
		}

		else if (result == -1) {
			cout << "Data Saved, Have a Great Day :)" << endl;
			break;
		}

		else {
			cout << "Something went terribly wrong, we apologize :(" << endl;
		}
	}

	finish();

	return 0;
}