Delphi: Detect if registry value exists

[BrainDrain]

In my application a checkbox is ticked to show if the Run On Startup key for it exists, when the app starts this code is used:

Reg.RootKey := HKey_Local_Machine;

Reg.OpenKey('\Software\Microsoft\Windows\CurrentVersion\Run',false);

IF Reg.ValueExists('Test') then

Checkbox1.checked:=true;

else

CheckBox1.Checked:=false;

However it doesn't do anything, I am looking at the string value "Test" in the registry at the above key. If anyone could work out why it's not doing anything it would be appreciated.

Edited January 1, 2007 by BrainDrain

[FAT64]

Try ...

IF Reg.OpenKey('\Software\Microsoft\Windows\CurrentVersion\Run',false) THEN

IF Reg.ValueExists('Test') THEN

Checkbox1.checked := true;

ELSE

CheckBox1.Checked := false;

... although it might be safer as an exception

TRY

IF Reg.OpenKey('\Software\Microsoft\Windows\CurrentVersion\Run',false) THEN

IF Reg.ValueExists('Test') THEN

Checkbox1.checked := true;

ELSE

CheckBox1.Checked := false;

EXCEPT/FINALLY

END

[BrainDrain]

I've tried using the code given above, but that didn't affect Checkbox1.visible at all (It stayed ticked or unticked unless I actually clicked it)

, I tried setting reg.Rootkey, as in this code:

TRY
 reg.RootKey:=HKEY_LOCAL_MACHINE;
IF Reg.OpenKey('\Software\Microsoft\Windows\CurrentVersion\Run',false) THEN
IF Reg.ValueExists('Test') THEN
Checkbox1.checked := true
ELSE
CheckBox1.Checked := false;
EXCEPT
END;
end;

But that causes an Access Violation when ran

Edited January 1, 2007 by BrainDrain

[Yzöwl]

Are you sure you have access rights, HKLM requires Administrator rights for read/write, unless you state that you are reading or you set the access rights first.

As we cannot see the rest of your code, I'm guessing you're using TRegistry; since you are only reading the key you could use

reg := TRegistry.Create (KEY_READ);
reg.RootKey :=HKEY_LOCAL_MACHINE;
try
If reg.OpenKey('\Software\Microsoft\Windows\CurrentVersion\Run', FALSE) then;

[BrainDrain]

Thanks for that, I have admin rights and am using TRegistry, I'll try that code and get back

EDIT:

I made a mistake, I'm trying to detect if a Value in a key exists,

reg.RootKey:=HKEY_LOCAL_MACHINE;
IF Reg.OpenKey('\Software\Microsoft\Windows\CurrentVersion\Run',false) THEN
IF Reg.ValueExists('Test') THEN
Checkbox1.checked := true

Would do exactly what I'm after if it worked, Sorry for getting that wrong

I've found that

reg.RootKey:=HKEY_LOCAL_MACHINE;
IF Reg.OpenKey('\Software\Microsoft\Windows\CurrentVersion\Run',false) THEN Application.Terminate;

doesn't do anything either, Its starting to sound like a permissions problem, but I can write and delete string values fine

Edited January 1, 2007 by BrainDrain

[Yzöwl]

Since it is not my language of choice, here is an 'educated, (or maybe not)', suggestion:

var
	Reg : TRegistry;
begin
	Reg := TRegistry.Create;
	Reg.RootKey := HKEY_LOCAL_MACHINE;
	KeyName := 'Software\Microsoft\Windows\CurrentVersion\Run';
	Checkbox1.checked := false;
	try
		Reg.OpenKeyReadOnly(KeyName);
		if Reg.ValueExists('Test') then Checkbox1.checked := true;
	finally
		Reg.CloseKey;
		Reg.Free;
	end;
end;