How to check if app already running?

[LucieLastic]

hi All

I did this many moons ago for a screen saver type program but can't remember how, the old grey cells are letting me down again.

How do you check if an app is already running ? In this case we want to check Excel isn't already running. I'm thinking of CreateProcess for some reason, then FindWindow....bah, humbug! can't remember....

Many thanks for help
lou

 

[saif]

write following code in project file

program Project1;

uses
Forms,
Dialogs,
Unit1 in 'Unit1.pas' {Form1},
Unit2 in 'Unit2.pas';

{$R *.res}

begin

if OnlyOneRunning then
begin
Application.Initialize;
Application.CreateForm(TForm1, Form1);
Application.Run;
end;
end.

write following code in Unit1 having main form

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
Button1: TButton;
procedure FormShow(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

uses Unit2;

{$R *.dfm}

procedure TForm1.FormShow(Sender: TObject);
begin
//ShowMessage(String(UniqueAppStr));
ShowMessage(String(unit2.UniqueAppStr));
end;

end.

write following code in Unit2
unit Unit2;

interface

function OnlyOneRunning:Boolean;

implementation
uses windows;

function OnlyOneRunning:Boolean;
var
myMutex:THandle;
begin
myMutex:=createmutex(nil, False,'MyUniqueProgramNameGoesHere');
Result:=WaitForSingleObject(myMutex,0) <> wait_timeout;
end;

end.

 

[saif]

write following code in project file

program Project1;

uses
Forms,
Dialogs,
Unit1 in 'Unit1.pas' {Form1},
Unit2 in 'Unit2.pas';

{$R *.res}

begin

if OnlyOneRunning then
begin
Application.Initialize;
Application.CreateForm(TForm1, Form1);
Application.Run;
end;
end.

write following code in Unit1 having main form

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
Button1: TButton;
procedure FormShow(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

uses Unit2;

{$R *.dfm}

procedure TForm1.FormShow(Sender: TObject);
begin
ShowMessage(String(unit2.UniqueAppStr));
end;

end.

write following code in Unit2
unit Unit2;

interface

function OnlyOneRunning:Boolean;

implementation
uses windows;

function OnlyOneRunning:Boolean;
var
myMutex:THandle;
begin
myMutex:=createmutex(nil, False,'MyUniqueProgramNameGoesHere');
Result:=WaitForSingleObject(myMutex,0) <> wait_timeout;
end;

end.

 

[LucieLastic]

CreateMutex, ofcourse! Many thanks, Saif, all comes flooding back now )

lou

 

[mikeEd]

Just out of interest, how do you use CreateMutex to determine whether or not Excel is running?

 

[LucieLastic]

hi Mike

I think you're right, you can't find out if Excel is running from here. As I'm not working on this bit yet I hadn't given it much thought. The Mutex eg. is for checking instances of one's app.

I think FindWindow is looking the best option at the mo., do you have any suggestions ?

thanks
lou

 

[mikeEd]

Yeah I'd use FindWindow.