Pascal Text Menu Issues

Question

So I'm trying to make a Pascal text program that allows the user to enter the name, genre, artist etc. of an album, and also view, play, update the album through 4 menu options. But im having issues as when I try to enter the first menu (the menu to add a new album), it just re prints the main menu. I'm using Sublime text editor and Mingw as a terminal. Here is the code, I believe the issue involves functions GetAlbum and GetAlbums.

Thanks :)

program TextMusicPlayer;
uses TerminalUserInput;

type
    Tracks = record
       name: String;
    end;

    Album = record
       name: String;
       artist: String;
       genre: String;
       track: array of String;
       key: Integer;
       trackcount: integer;
    end;

    playlist = array of Album;

function GetAlbum( var myFile: TextFile): Album;
var
   albumInfo: Album;
   i: Integer;
begin
   albumInfo.name := ReadString('Enter name: ');
   albumInfo.artist := ReadString('Enter artist: ');
   albumInfo.genre := ReadString('Enter genre: ');
   albumInfo.trackcount := ReadInteger('Enter track no.: ');
   SetLength(albumInfo.track, albumInfo.trackcount); 
   for i := 0 to High(albumInfo.track) do
   begin
      ReadLn(myFile, albumInfo.track[i]);
   end;
   albumInfo.key := -1;
   result := albumInfo;
   Close(myFile);
end;

function GetAlbums(): playlist;
var
    myFile: TextFile;
    playlist: array of Album;
    i, r: integer;
begin
    AssignFile(myFile, 'music.txt');
    Reset(myFile);
    ReadLn(myFile, r);
    SetLength(playlist, r);
    for i := 0 to High(playlist) do
        begin
            playlist[i] := GetAlbum(myFile);
        end;
    result := playlist;
end;

function PrintAllAlbums(playlist: playlist): playlist;
var
    i: integer;
begin
    for i := 0 to High(playlist) do
    begin
       playlist[i].key := i;
       WriteLn(playlist[i].name, ' key number: ', i);
    end;
    result := playlist;
end;

function PrintAllGenres(playlist: Playlist): Playlist;
var
   genre: String;
   i: Integer;
   r: Integer;
   m: Integer;
begin
   m := 0;
   for i := 0 to High(playlist) do
   begin
      playlist[i].key := -1;
   end;

   genre := ReadString('Enter the Genre: ');

   for r := 0 to High(playlist) do
   begin
      if (genre = playlist[r].genre) then
      begin
         playlist[i].key := m;
         WriteLn(playlist[r].name, ' key number: ', m);
         m := m + 1;
      end;
    end;
    result := playlist;
end;

function PrintAlbums(playlist: playlist): playlist;
var
    val: integer;
begin
    WriteLn('***Displaying Albums***');
    WriteLn('1 - Display all albums');
    WriteLn('2 - Display all of one genre');
    WriteLn('3 - Back to Main Menu');
    val := ReadInteger('Enter a number to enter a Menu: ');

    case val of
       1: playlist := PrintAllAlbums(playlist);
       2: playlist := PrintAllGenres(playlist);
    end;
    result := playlist;
end;

procedure PlayAlbum(albumInfo: Album);
var
   i: Integer;
   r: Integer;
begin
    WriteLn('Album:', albumInfo.name);
    for i := 0 to High(albumInfo.track) do
    begin
       WriteLn(i + 1, albumInfo.track[i]);
    end;
    r := ReadInteger('Select a track number to play: ');
    while (r < 1) or (r > (High(albumInfo.track) + 1)) do
    begin
       r := ReadInteger('Please select a track number from above: ');
    end;
    WriteLn('Playing track ', r, albumInfo.track[(r - 1)], ' from the album ', albumInfo.name);
    ReadString('Press Enter to return to Main Menu ');
end;

procedure SelectAlbum(playlist: Playlist);
var
   val: Integer;
   i: Integer;
   r: Integer;
begin
   r := 0;
   WriteLn('***Welcome to the Track Player***');
   val := ReadInteger('Enter an Albums key number');
   for i := 0 to High(playlist) do
   begin
      if (playlist[i].key = val) then
      begin
         PlayAlbum(playlist[i]);
      end
      else
      begin
         r := r + 1;
      end;
   end;
   if r > High(playlist) then
   begin
      WriteLn('Album was not found, now returning to Main Menu ');
   end;
end;

function ChangeAlbum(albumInfo: Album): Album;
begin
    albumInfo.name := ReadString('Please enter a new name for this album');
    albumInfo.genre := ReadString('Please enter a new gernre for this album');
    result := albumInfo;
end;

function ChangeAlbums(playlist: Playlist): Playlist;
var
   val: Integer;
   i: Integer;
   j: Integer;
begin
   j := 0;
   WriteLn('***Album Updater***');
   val := ReadInteger('Enter an Albums key number: ');
   for i := 0 to High(playlist) do
   begin
      if (playlist[i].key = val) then
        begin
         playlist[i] := ChangeAlbum(playlist[i]);
        end
      else
        begin
         j := j + 1;
        end;
    end;
   if j > High(playlist) then
   begin
      WriteLn('Album was not found, now returning to Main Menu ');
   end;
   result := playlist;
end;

procedure Main();
var
    i, val: Integer;
    playlist: array of Album;
begin
    i := 0;
    while (i = 0) do
    begin
       WriteLn('');
       WriteLn('***Text Music Player Menu***');
       WriteLn('1 - Add new Albums');
       WriteLn('2 - View Albums');
       WriteLn('3 - Play an Album');
       WriteLn('4 - Update an Album');
       WriteLn('5 - Quit');
       val := ReadInteger('Enter a number to enter a Menu: '); 

       case val of
          1: playlist := GetAlbums();
          2: playlist := PrintAlbums(playlist);
          3: SelectAlbum(playlist);
          4: playlist := ChangeAlbums(playlist);
       else
          i := i + 1;
       end;
    end;
end;

begin
    Main();
end.

All written right. You just read album in memory then programm waits your next step displaying main menu. Type two if you want to see the album — user3811082
the program im having is that it doesnt let me give an input of the album information — PYUO
Have you stepped through your code? It seems to me that if you are not allowed to enter the album information it must be because the GetAlbum is not being called which implies the for loop is not running. — juus
Which Pascal is this? The Pascals I have (FreePascal, Delphi) don't have a unit TerminalUserInput, so I can't try your code. — Rudy Velthuis
In GetAlbums (plural), you are opening 'music.txt' to read from it. But you only read one value, the size of the playlist. Then you use GetAlbum (singular) to get that many albums from the user. That is not how it should be. You should get an album from the user and then append it to your music.txt file, somehow. In other words: there is an error in your logic. — Rudy Velthuis

hix hix · Accepted Answer · 2017-05-22T16:20:03

In an attempt to modularise you code you have actually made it a lot harder for others and even yourself to understand what is effectively going on. I believe a much more simpler approach would be just having a single procedure to read in the album from the text file.

Also I think a more suitable approach to getting user input for the menu would be like this

    repeat
     val := ReadInteger('Enter a number to enter a Menu: ');
        case val of
              1: playlist := GetAlbums();
              2: playlist := PrintAlbums(playlist);
              3: SelectAlbum(playlist);
              4: playlist := ChangeAlbums(playlist);
    until val = 5 
    end;

Pascal Text Menu Issues

1 Answers