Pascal: Will not read anything from my file and getting errors - pascal

Question

I've been stressing out for the past few hours trying to get this working and I simply cannot figure it out. Basically it doesn't read anything from my .dat file and when I try to use options 2, 3 or 4 it just comes up with these
.
I've include the .dat file and pascal below. I'm desperate for help.
mytestfile.dat
1
Adele
Pop
2
Hello
ff
Remedy
dd
pascal
program MusicPlayer;
uses TerminalUserInput;
type
TrackRec = record
name: String;
location: String;
end;
// type TrackArray = array of TrackRec;
GenreType = (Pop, Rap, Rock, Classic);
AlbumRec = Record
name: String;
genre: GenreType;
// location: array of TrackRec;
tracks: array of TrackRec;
end;
type AlbumArray = array of AlbumRec;
function ReadGenre(): GenreType;
var
option: Integer;
begin
WriteLn('Press 1 for Pop');
WriteLn('Press 2 for Rap');
WriteLn('Press 3 for Rock');
WriteLn('Press 4 for Classic');
option := ReadInteger('');
while (option<1) or (option>5) do
begin
WriteLn('Please enter a number between 1-4');
option := ReadInteger('');
end;
case option of
1: result := Pop;
2: result := Rap;
3: result := Rock;
else
result := Classic;
end;
end;
procedure NewAlbum(var albums: AlbumArray; var myFile: TextFile);
var
number, i, tracks, y: Integer;
begin
AssignFile(myFile, 'mytestfile.dat');
ReWrite(myFile);
number := ReadInteger('How many albums do you want to make?: ');
WriteLn(myFile, number);
SetLength(albums, number);
for i := Low(albums) to High(albums) do
begin
albums[i].name := ReadString('Enter album name:');
WriteLn(myFile, albums[i].name);
albums[i].genre := ReadGenre();
WriteLn(myFile, albums[i].genre);
tracks := ReadIntegerRange('How many tracks do you want to enter? (max 15)', 0, 15);
WriteLn(myFile, tracks);
SetLength(albums[i].tracks, tracks);
for y := Low(albums[i].tracks) to tracks - 1 do
begin
albums[i].tracks[i].name := ReadString('Track name:');
WriteLn(myFile, albums[i].tracks[i].name);
albums[i].tracks[i].location := ReadString('Track Location:');
WriteLn(myFile, albums[i].tracks[i].location);
end;
end;
Close(myFile);
end;
procedure ReadTrack(count: Integer; var albums: AlbumArray; var myFile: TextFile);
var
i: Integer;
begin
ReadLn(myFile, i);
SetLength(albums[count].tracks, i);
for count := Low(albums[count].tracks) to High(albums[count].tracks) - 1 do
begin
ReadLn(myFile, albums[count].tracks[i].name);
ReadLn(myFile, albums[count].tracks[i].location);
end;
end;
procedure ReadAlbum(var albums: AlbumArray; var myFile: TextFile);
var
albumNumber, tracknumber, count, i: Integer;
begin
AssignFile(myFile, 'mytestfile.dat');
Reset(myFile);
ReadLn(myFile, albumNumber);
SetLength(albums, albumNumber);
for i := Low(albums) to High(albums) do
begin
ReadLn(myFile, albums[i].name);
ReadLn(myFile, albums[i].genre);
ReadLn(myFile, tracknumber);
SetLength(albums[i].tracks, tracknumber);
for count := Low(albums[count].tracks) to tracknumber - 1 do
begin
ReadLn(myFile, albums[count].tracks[i].name);
ReadLn(myFile, albums[count].tracks[i].location);
end;
end;
end;
procedure ReadAlbums(var albums: AlbumArray; var myFile: TextFile);
var
i, number: Integer;
begin
ReadAlbum(albums, myFile);
WriteLn('Album is:');
for i := Low(albums) to High(albums) do
begin
WriteLn((i + 1),'.', albums[i].name);
WriteLn('.', albums[i].genre);
for number := Low(albums[i].tracks) to High(albums[i].tracks) do
begin
WriteLn((number + 1), '', albums[i].tracks[Low(albums[i].tracks)].name);
end;
end;
end;
procedure PlayAlbum (var albums: AlbumArray; var myFile: TextFile);
var
i, number: Integer;
begin
ReadAlbums(albums, myFile);
i := ReadInteger('Please select an album: ');
i := i - 1;
number := ReadIntegerRange('Please select a song from album:', 1, 20);
number := number - 1;
WriteLn('Now playing');
WriteLn('Track selected: ', albums[i].tracks[number].name);
WriteLn('Album: ', albums[i].name);
end;
procedure Update(var albums: AlbumArray; var myFile: TextFile);
var
i: Integer;
begin
ReadAlbums(albums, myFile);
i := ReadInteger('Select an album to update');
i := i - 1;
albums[i].name := ReadString('New Album Name:');
WriteLn('Album has now been updated');
end;
procedure Main();
var
i, count, select, change: Integer;
albums: AlbumArray;
myFile: TextFile;
begin
WriteLn('Please select an option: ');
WriteLn('-------------------------');
WriteLn('1. Read Albums');
WriteLn('2. Display Albums');
WriteLn('3. Select an Album');
WriteLn('4. Update an Album');
WriteLn('5. Exit');
WriteLn('-------------------------');
repeat
i := ReadInteger('Select option for menu:');
case i of
1: ReadAlbum(albums, myFile);
2: ReadAlbums(albums, myFile);
3: PlayAlbum(albums, myFile);
4: Update(albums, myFile);
end;
until i = 5;
end;
begin
Main();
end.

Answer 1

In the ReadAlbum() procedure you have two for loops, an outer one that loops through the albums and an inner one that loops through the tracks. In the latter you have messed up the indexes:
This is the erroneous code:
for count := Low(albums[count].tracks) to tracknumber - 1 do
begin
ReadLn(myFile, albums[count].tracks[i].name);
ReadLn(myFile, albums[count].tracks[i].location);
end;
albums[] should use i as index and tracks[] should use count as index.
Until you get more used to arrays and indexes I suggest you name your variables with a clear meaning, for example:
`NumOfAlbums` in the meaning of how many albums you have
`AlbumIndex` as the index to the albums array
`NumOfTracks` as the number of tracks in an album
`TrackIndex` as the index to the tracks array
It may feel tiresome to write so long names, but you would probably not have made the mistake you did, with the more verbose names.