Can't open PDF, is there a way to detect if it opens?

Question

I'm writing a C# Windows program. On a form, I have a list of websites and PDFs. When they click on a PDF, the code downloads that file, then tries to open it. On my Windows 8 machine, the PDFs open fine. On Windows 7 and XP machines, they are not opening and there are no visual clues showing where things are breaking. (On both of these machines, you can click on a PDF in the file explorer and the PDFs will open.)

I started by looking at Opening a pdf in .NET, then added to that. Here's what I' using...

if (File.Exists(localFileName))
{
    //MessageBox.Show("calling file " + localFileName, "FYI...");
    System.Diagnostics.Process process = new System.Diagnostics.Process();
    System.Diagnostics.ProcessStartInfo startInfo = new System.Diagnostics.ProcessStartInfo();
    startInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
    startInfo.FileName = "cmd.exe";
    startInfo.Arguments = "call /c " + localFileName;
    process.StartInfo = startInfo;
    try
    {
        //MessageBox.Show("calling file " + localFileName, "FYI...");
        if (!process.Start())
        {
            MessageBox.Show("Could not invoke the PDF Viewer. Try opening the file at " + localFileName, 
                "Problem Opening File...", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
            return;
        }
    }
    catch (Exception exc)
    {
        MessageBox.Show("Couldn't start process (call " + localFileName + "), Message=" + exc.Message, 
        "Problem Encounter...", MessageBoxButtons.OK, MessageBoxIcon.Error);
        return;
    }
    //MessageBox.Show("Should be done", "FYI...");
}

I am trying to detect whether the process starts or not. If I can't get them to execute, it would help if I could display a message telling the user where to look to open the downloaded file. Any thoughts?

Answer 1

Your code is totally wrong. There is absolutely no need for cmd.exe to be involved in this operation, nor is there a need for call /c (and there's absolutely no need to require elevation as your answer suggests).

if FileExists(localFileName) {
    try
    { 
      System.Diagnostics.Process.Start(localFileName); 
    catch
    }
      /* 
         Handle failure to start process (Win32Exception)
         No need to handle FileNotFoundException, because
         you can do that in the else below
      */
    };
}
else
{
  // Handle missing file
}

cmd.exe is not needed, as it opens a new instance of the Windows command processor (AKA a command prompt), and call /c is only needed when CALLing another batch file from within a batch file. There is certainly no need to elevate the process as your answer suggests.

Answer 2

The problem appears to be permission-related. I added process.Verb = "runas" to bump it up to admin level and it worked on the Windows 7 machine. On the XP machine, it prompted for an admin password, which isn't great but should be good enough for my purposes...