How to detect application associated with file

To get full path to application associated with any file type, we need standard ShellAPI unit and the rest will do the FindExecutable function.

 This function retrieves the name of and handle to the executable (.exe) file associated with a specific document file. For more information, visit detailed description on MSDN.

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ShellAPI;
 
type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.Button1Click(Sender: TObject);
var app: PChar;
begin
  GetMem(app, 255);
  FindExecutable('test.txt', 'c:\', app);
  Application.MessageBox(App, 'Associated application', mb_ok + 

           mb_iconinformation);
end;
 
end.