Running an external program using ShellExecute

Question

As far as i know ... You need to set the executable program in ShellExecute (like notepad.exe) but what if the user wants to use other external program (like notepad++.exe) to open the file? if this is possible then how will i do that?

Answer 1

My guess is that what you really want to do is open a document using whatever program the user has chosen to associate with that document type. In which case you pass the document to ShellExecute rather than the program:

ShellExecute(0, nil, PChar(DocumentFileName), nil, nil, SW_SHOWNORMAL);

Passing nil for the second parameter, the verb, uses the default verb for the document. Usually this will be the 'open' verb. But not always. So you might instead write:

ShellExecute(0, 'open', PChar(DocumentFileName), nil, nil, SW_SHOWNORMAL);

If you want to be able to check for errors in a sane way you will need to use ShellExecuteEx rather than ShellExecute.

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Your comments shed a little more light on the question, although I'm still clutching at straws. You seem to want to be able to open an RTF file in the user's preferred text editor. Do that using ShellExecuteEx passing a class name that instructs the shell to treat the file as if it were text.

var
  sei: TShellExecuteInfo;
....
ZeroMemory(@sei, SizeOf(sei));
sei.cbSize := SizeOf(sei);
sei.fMask := SEE_MASK_CLASSNAME;
sei.lpVerb := 'open';
sei.lpFile := PChar(DocumentFileName);
sei.nShow := SW_SHOWNORMAL;
sei.lpClass := '.txt';
Win32Check(ShellExecuteEx(@sei));