Pascal: Je ne lirai rien de mon fichier et j'obtiendrai des erreurs

Question

Je me suis stressé ces dernières heures en essayant de faire fonctionner ça et je n'arrive tout simplement pas à comprendre. Fondamentalement, il ne lit rien de mon fichier .dat et quand j'essaie d'utiliser les options 2, 3 ou 4, il vient avec ces

.

J'ai inclus le fichier .dat et pascal ci-dessous. Je suis désespéré de l'aide.

mytestfile.dat

1 
Adele 
Pop 
2 
Hello 
ff 
Remedy 
dd 

pascals

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

Dans la procédure ReadAlbum() vous avez deux boucles for, une extérieure qui boucle à travers les albums et un intérieur qui une boucle à travers les pistes. Dans ce dernier, vous avez foiré les index:

Ce code erroné:

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[] devrait utiliser i comme index et tracks[] devrait utiliser count comme indice.

Jusqu'à ce que vous obtenez plus utilisé pour les tableaux et les indices que je vous suggère de nommer vos variables avec un sens clair, par exemple:

`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 

Il peut se sentir fastidieux d'écrire les noms si longtemps, mais vous auriez probablement pas fait l'erreur que vous avez faite, avec les noms les plus verbeux.