Question

How could I create a Console Application that could work with or without a GUI?

For example, say if I had a console application, If i tried launching this console app from Windows Explorer it will not work it will just close, but I could call it from my GUI Application or the Windows Command Console (cmd.exe) and pass some switches (parameters?) to it.

That way some useful functions can be used without even starting the GUI Application, they can be called from the command line.

EDIT

I am not sure how to create the Console Application, especially that would accept flags (switches, parameters?).

I have seen some Applications that do something similar. For example they might have a Console Application that will convert a bmp to a png, and the GUI calls this Console Application and passes the arguments etc to it.

Hope that makes sense.

So how could I employ something like this?

Thanks.

Answer 1

For example, say if I had a console application, If i tried launching this console app from Windows Explorer it will not work it will just close, but I could call it from my GUI Application or the Windows Command Console (cmd.exe) and pass some switches (parameters?) to it.

It will work. However, the console window will disappear as soon as your program has exited. If you want to give the user a chance to read the output of your console application before the window is closed, simply end your program with a single

Readln;

or

Writeln('Press Enter to exit.');
Readln;

If you want to use a console window for output (or input) in a GUI application, you can give the AllocConsole and FreeConsole functions a try.

Command-line arguments (such as myapp.exe /OPEN "C:\some dir\file.txt" /THENEXIT) can be used in all types of Windows applications, both GUI apps and console apps. Just use the ParamCount and ParamStr functions.

How to Create a Console Application that Accepts Command-Line Arguments

In the Delphi IDE, choose File/New/Console Application. Then write

program Project1;

{$APPTYPE CONSOLE}

uses
  Windows, SysUtils;

var
  freq: integer;

begin

  if ParamCount = 0 then
    Writeln('No arguments passed.')

  else if ParamCount >= 1 then

    if SameText(ParamStr(1), '/msg') then
    begin

        if ParamCount = 1 then
          Writeln('No message to display!')
        else
          MessageBox(0, PChar(ParamStr(2)), 'My Console Application',
            MB_ICONINFORMATION);

    end

    else if SameText(ParamStr(1), '/beep') then
    begin

      freq := 400;

      if ParamCount >= 2 then
        if not TryStrToInt(ParamStr(2), freq) then
          Writeln('Invalid frequency: ', ParamStr(2));

      Windows.Beep(freq, 2000);

    end;


end.

Compile the program. Then open a command processor (CMD.EXE) and go to the directory where Project1.exe is.

Then try

C:\Users\Andreas Rejbrand\Documents\RAD Studio\Projects>project1
No arguments passed.

C:\Users\Andreas Rejbrand\Documents\RAD Studio\Projects>project1 /msg
No message to display!

C:\Users\Andreas Rejbrand\Documents\RAD Studio\Projects>project1 /msg "This is a test."

C:\Users\Andreas Rejbrand\Documents\RAD Studio\Projects>project1 /beep

C:\Users\Andreas Rejbrand\Documents\RAD Studio\Projects>project1 /beep 600

C:\Users\Andreas Rejbrand\Documents\RAD Studio\Projects>

How to pass three arguments

if ParamCount >= 1 then
begin

  if SameText(ParamStr(1), '/CONVERT') then
  begin

    // The user wants to convert

    if ParamCount <= 2 then
    begin
      Writeln('Too few arguments!');
      Exit;
    end;

    FileName1 := ParamStr(2);
    FileName2 := ParamStr(3);

    DoConvert(FileName1, FileName2);

  end;

end;