How do I solve I/O error 103 in delphi

Question

So Basically I'm in College in the UK (So that's school for Americans (17 years old)) and I have to make a file handling project for my finals. I have done most of it but it's the login screen that is weighing me down a lot. What I want from the program to do is read the username and password and log the people in. There can be 2 different outputs. If you type in "Staff" in the username and "warwickschool2013" in the username, the program takes you to the "teacher" side of the program where they can add in new users.

unit LoginScreen;
interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, jpeg, ExtCtrls;

type
  TfrmLogin = class(TForm)
    lblWelcomeLogin: TLabel;
    edtPassword: TEdit;
    lblPassword: TLabel;
    btnLogin: TButton;
    btnClose: TButton;
    lblCounter: TLabel;
    lblAttempts: TLabel;
    Image1: TImage;
    edtUsername: TEdit;
    lblUserName: TLabel;
    procedure btnCloseClick(Sender: TObject);
    procedure btnLoginClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  frmLogin: TfrmLogin;


implementation
uses MainMenu, TeachersMainMenu, ViewEditTheData, Globals_Unit;
var
LoginDataArray: array of TLoginData;
counter: integer;
Password, username : String;
Count1, Count2 : integer;
Temp: TLoginData;

{$R *.dfm}

procedure TfrmLogin.btnLoginClick(Sender: TObject);
var
SearchName : string[10];
SearchCode : string[3];
begin
  Password:=edtPassword.Text;
  UserName:=edtUserName.Text;
  btnclose.enabled:= true;
 if (Password = 'warwickschool2013') AND (Username = 'Staff') then
   begin
     edtPassword.text :='';
     frmTeachersMainMenu.show;
     frmLogin.hide;
     counter:= 0;
     lblCounter.caption := IntToStr(Counter);
  end
  else
   begin
     assignfile      (LoginDatafile,'C:\Users\NinjaBoffin\Desktop\Delphi\DataFiles\LoginData.txt');
     reset (LoginDatafile);
     LoginDatacounter := FileSize(LoginDatafile);
     SetLength(LoginDataArray, LoginDatacounter);
     edtPassword.clear;
     edtUserName.Clear;
     for Count1 := 1 to LoginDataCounter  do
       begin
          read(LoginDatafile,SingleLoginData);
          LoginDataArray[Count1] := SingleLoginData;
       end;
      closefile (LoginDatafile);

      //bubble sort
      edtUserName.Clear;
      for count1 := 1 to LoginDatacounter-1 do
         for count2 := 1 to LoginDatacounter-1 do
            if LoginDataArray[count2].UserName > LoginDataArray[count2+1].UserName then
           begin
             temp := LoginDataArray[count2+1];
             LoginDataArray[count2+1] := LoginDataArray[count2];
             LoginDataArray[count2] := temp;
           end;
//Linear Search (files getting ready)
begin
  SearchName := edtUserName.text;
  assignfile     (LoginDatafile,'C:\Users\NinjaBoffin\Desktop\Delphi\DataFiles\LoginData.txt');
  reset (LoginDatafile);
  LoginDatacounter := FileSize(LoginDatafile);
  SetLength(LoginDataArray, LoginDatacounter);
  edtUserName.Clear;
  //Copying to array
  for  Count1 := 1 to StudentCounter do
   begin
      read(LoginDatafile,SingleLoginData);
      LoginDataArray[Count1] := SingleLoginData;
   end;
  closefile (Studentfile);
 //The actual linear search
for  Count1 := 1 to StudentCounter do
 begin
   if LoginDataArray[Count1].Username = SearchName then
    begin
      assignfile    (LoginDatafile,'C:\Users\NinjaBoffin\Desktop\Delphi\DataFiles\LoginData.txt');
      reset (LoginDatafile);
      LoginDatacounter := FileSize(LoginDatafile);
      SetLength(LoginDataArray, LoginDatacounter);
      edtPassword.clear;
      for Count1 := 1 to LoginDataCounter  do
        begin
          read(LoginDatafile,SingleLoginData);
          LoginDataArray[Count1] := SingleLoginData;
        end;
        closefile (LoginDatafile);
        //bubble sort
       edtUserName.Clear;
       for count1 := 1 to LoginDatacounter-1 do
         for count2 := 1 to LoginDatacounter-1 do
             if LoginDataArray[count2].Password > LoginDataArray[count2+1].Password then
                begin
                  temp := LoginDataArray[count2+1];
                  LoginDataArray[count2+1] := LoginDataArray[count2];
                  LoginDataArray[count2] := temp;
                end;
   //Linear Search (files getting ready)
   begin
      SearchName := edtPassword.text;
      assignfile (LoginDatafile,'C:\Users\NinjaBoffin\Desktop\Delphi\DataFiles\LoginData.txt');
      reset (LoginDatafile);
      LoginDatacounter := FileSize(LoginDatafile);
      SetLength(LoginDataArray, LoginDatacounter);
      edtPassword.clear;
      //Copying to array
      for  Count1 := 1 to StudentCounter do
       begin
        read(LoginDatafile,SingleLoginData);
        LoginDataArray[Count1] := SingleLoginData;
       end;
       closefile (Studentfile);
      //The actual linear search
       for  Count1 := 1 to StudentCounter do
         begin
           if LoginDataArray[Count1].Password = SearchName then
             begin
               frmLogin.Hide;
                frmMainmenu.Show;
             end;
          end;
        end;
   end;
  end;
 end;
 end;
end;

If that is not the username and password you have to enter the password and username made by the teacher for you. This is in the teachers form and the file is "Logindata.txt".

procedure TfrmAddNewUser.btnAddNewStudentClick(Sender: TObject);
begin
  assignfile (LoginDataFile,'C:\Users\NinjaBoffin\Desktop\Delphi\DataFiles\LoginData.txt');
  reset (loginDataFile);
  LoginDataCounter := FileSize(LoginDataFile);
  SingleLoginData.Username := edtNewUsername.text;
  SingleLoginData.Password := edtNewPassword.Text;
  //find where to store the record
  seek (LoginDataFile,LoginDataCounter);
  {...and put the record in}
  write(LoginDataFile,SingleLoginData);
  closefile (LoginDataFile);
  edtNewUserName.Text := '';
  edtNewPassword.Text := '';
end;

I'm getting a constant I/O 103 error and I don't know where it's from (It's in the login form) So how do I fix this error? and will the login work?

This is my first time programming

Answer 1

Thank You Guys for solving the problem (I/O error 103) Turns out i was closing file that didn't exist

Closefile (StudentFile)

When it should have been

Closefile (LoginDataFile)

Thanks to everyone who helped

Answer 2

I'm late for your finals, but maybe this can help for future projects. You can use an approach based on name-values pairs and on TStringLIst object ability to load and save text files, so you don't have to care about files handles:

const
  MyFileWithPath='c:\.......\UserList.txt';

procedure AddUser(UserId,UserPwd: string);
var
  l: TStringList;
begin
  l := TStringList.Create;
  try
    if FileExists(MyFileWithPath) then
      l.LoadFormFile(MyFileWithPath);
    l.Add(Format('%s=%s',[UserId,UserPwd]));
    l.SaveToFile(MyFileWithPath);
  finally
    l.Free;
  end;
end;

function GetUserPwd(UserId: string): string;
var
  l: TStringList;
begin
  l := TStringList.Create;
  try
    l.LoadFormFile(MyFileWithPath);
    Result := l.Values[UserId];
  finally
    l.Free;
  end;
end;

You can complete this simple basic pattern implementing a value structure if more data field are required.