use Console Application with GUI Application? - delphi

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;

Answer 2

That way some useful functions can be used without even starting the GUI Application, they can be called from the command line.
If you want the application to be a GUI application, but you want to override the GUI by passing command line parameters, then try someting like this:
program Project1;
uses
Forms,
SysUtils,
Windows,
Unit1 in 'Unit1.pas' {Form1};
{$R *.res}
begin
if ParamCount > 0 then
Windows.MessageBox(GetDesktopWindow, PChar(ParamStr(1)), PChar('Test'), 0)
else
begin
Application.Initialize;
Application.CreateForm(TForm1, Form1);
Application.Run;
end;
end.

Answer 3

I am not sure how to achieve this in delphi but in C# I just checked in the Main method if any command line arguments had been passed in, if there were then run the application with a console if there were none run the GUI.