Creating a login if data does not exist.

[kirk]

Hi there. Being as this is my first post, I've tried my best to sort this problem through many books, Google searches and topics on file I/O reading and writing before posting - to no avail.

I've created a file which stores usernames & passwords and all is fine, but when I try to add the condition that returns a null value, (EG There is no existing data that matches in the file), I get one of two errors: A. Expected primary expression before ')' token. OR B. Username will always return true.

The piece code in question is in bold. Any help would be appreciated. Thank you!

#include <iostream>
#include <fstream>
#include <cstdlib>
#include <cstdio>
#include <string>

using namespace std;

int main()
{

string username;    
string password;    
char response = ('y' || 'n');

    cout << "THE DESCENDANT\n";             
    cout << "Welcome to the Game!\n\n\n";

    cout << "Please enter your username: "; 
    cin >> username;                        

    cout << "Please enter your password: "; 
    cin >> password;
                     
    ifstream inuserdata("USER_ID.txt");
    if (!inuserdata) {
        cout << "Cannot open file.\n";
        return 1;
    }

    inuserdata >> username;
    inuserdata >> password;

    inuserdata.close();

 if (username = !)
    {
        cout << "No previous game data was detected. Would you like to start a new game? (Y/N)";
        cin >> response;
        if (response == 'y')
        {
            cout << "Please enter a username: "; 
            cin >> username;                        

            cout << "Please enter a password: "; 
            cin >> password;                        

            ofstream outuserdata("USER_ID.txt", ios::app);
            if(!outuserdata) {                                                                                               
                cout << "Cannot open file.\n";
                return 1;
            }

            outuserdata << username;   
            outuserdata << "\n";
            outuserdata << password;   
            outuserdata << "\n\n";

            outuserdata.close();   
        }
    }
        else
        {
            cout << "Thanks for playing. Good bye.\n";
        }

    system("PAUSE");    
    return 0;
}

[francesco919]

As I'm not a master in C++ programming, maybe i shouldn't take voice but I think that you have to compare username with something.

If you want to chech whether this user has played this game you should create a variable or list containing previous username(s).

It should look like this:

string last_username //or list of usernames here
...

if (username != last_username) //or check usernames list items here
...

Hope it helps...