How to get recommended programs associated with file extension in C#

Question

I want to get path to the programs that associated with file extension, preferably through Win32 API.

1. List of programs that appears in "Open With" menu item
2. List of programs that appears as recommended in "Open With..." dialog.

UPD:

Assume that i have office11 and office12 installed on my machine, default program for .xls is office 11. If look at HKEY_CLASSES_ROOT\Excel.Sheet.8\shell\Open\command there is a path to office11 excel.exe, but when i right click on file i can choose office12 in Open With menu item. So where is this association stored?

I'm using C#.

Thanks.

Answer 1

I wrote a small routine:

public IEnumerable<string> RecommendedPrograms(string ext)
{
  List<string> progs = new List<string>();

  string baseKey = @"Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\." + ext;

  using (RegistryKey rk = Registry.CurrentUser.OpenSubKey(baseKey + @"\OpenWithList"))
  {
    if (rk != null)
    {
      string mruList = (string)rk.GetValue("MRUList");
      if (mruList != null)
      {
        foreach (char c in mruList.ToString())
          progs.Add(rk.GetValue(c.ToString()).ToString());
      }
    }
  }

  using (RegistryKey rk = Registry.CurrentUser.OpenSubKey(baseKey + @"\OpenWithProgids"))
  {
    if (rk != null)
    {
      foreach (string item in rk.GetValueNames())
        progs.Add(item);
    }
    //TO DO: Convert ProgID to ProgramName, etc.
  }

  return progs;
  }

which gets called like so:

foreach (string prog in RecommendedPrograms("vb"))
{
  MessageBox.Show(prog);
}

Answer 2

Ever wanted to programmatically associate a file type on the system with your application, but didn't like the idea of digging through the registry yourself? If so, then this article and code are right for you.

System File Association