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source : http://www.festra.com

The following code shows how to disable or enable an individual radio button in a TRadioGroup component, the second radio button in our example. Note that the RadioGroup.Controls is a zero based array.

procedure TForm1.Button1Click(Sender: TObject);
begin
TRadioButton(RadioGroup1.Controls[1]). Enabled := False;
end;

source : http://www.festra.com

When creating a Delphi component dynamically (a form or whatever other component), in the Create method you have to specify its owner, for example:

Form2 := TForm2.Create(aOwner);

aOwner can be another object or nil (no owner):

- a component with an owner is destroyed automatically, when its owner is destroyed.

- a component without an owner (you passed nil as the owner) will not be destroyed automatically, so you must destroy (free) it yourself. Failing to do so leads to what is called “memory leaks”, that eventually could “hang” your program or even need a reboot of Windows.

Here are a few practical rules:

* If you dynamically create Form2 in the code of your main form Form1, and you want Form2 to be destroyed automatically at the end of the program, then pass Application as the owner.

* If you create Form3 in the code of another form Form2 (not the main form), and you want Form3 to be destroyed automatically when Form2 is destroyed, then pass self as the owner. The variable self in this case points to Form2.

* If you dynamically create a form (or any other component) and for some reason you want to explicitly free it sometime later, always pass nil as its owner. Otherwise, you run the risk that the component is “freed” twice, giving errors that are very difficult to debug.

Now, for some code examples.
1. Owner is another form

var
Form2: TForm2;

procedure TForm1…
begin
…
Form2 := TForm2.Create(Form1);

Form2 will be destroyed automatically when Form1 is destroyed. DO NOT “Free” Form2 yourself !

Instead of TForm2.Create(Form1) you will usually see:

var
Form2: TForm2;

procedure TForm1.SomeProcedure;
begin
…
Form2 := TForm2.Create(self);

The variable self is the object of which SomeProcedure is a method. That’s a complicated way of saying: in our example, self is the same as Form1. Thus, the two code examples above are equivalent.

2. Owner is the global variable Application

var
Form2: TForm2;

procedure TForm1…
begin
…
Form2 := TForm2.Create(Application);

Here, Form2 will be destroyed automatically when the Application is destroyed, that is: when the program stops.

3. Owner is nil

procedure TForm1.SomeProcedure;
var
FDialog: TForm2;
begin
FDialog := TForm2.Create(nil);
FDialog.ShowModal;
…
FDialog.Free;

In this case, the form FDialog does not have an owner, so you have to destroy FDialog yourself from the moment that it’s not needed anymore.

The µC/51 compiler is well known for it’s high quality and high density code. You can develop high quality software for any 8051 in ANSI C. µC/51 comes with an incredible optimizing compiler, you can even write software in ANSI C on 8051’s with 1kB of code memory! µC/51 is absolutely complete: user friendly multi file editor, compiler, assembler, downloader, source level debugger. It’s a complete toolchain - You won’t need anything else.

More …….

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Aside from basic functions such as the reading, programming, comparison copying and erasure of chips in the Batronix programming devices, the Prog-Studio 6 software offers numerous other functions. The Hex/ASCII editor gives you many options for working with the component contents, and the MC editor integrates a comprehensive compiler/assembler/debugger for developers of microcontroller applications.
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download :
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Manual Books

In this IC-Databook Software you will find pin assignments, connection layouts, function tables and the most important specifications available for the 40x.. and the 74x.. IC series.

Read the rest of this entry »

Here’s a quick and easy way to change your administrator password on Windows XP.

1. Place your Windows XP CD in your cd-rom and start your computer (it’s assumed here that your XP CD is bootable – as it should be - and that you have your bios set to boot from CD) Read the rest of this entry »

by Raymond on September 1st, 2006

There are many ways to login to a password protected Windows even if you do not have the password. You can reset the current password to a defined password, make your Windows accept any passwords or decrypted the current password. Read the rest of this entry »

written by : –BackDoor–

I. What Is A Proxy Server?
A proxy server is an interface between your browser and the destination server. The proxy server will take your page request and handles for your browser the connection to the destination. These proxy servers are also able to cache pages. If such a proxy is configured to cache it will at first take look to its local cache if the requested page already exist. If not it can search in other caching proxy servers or makes directly the request to the destination. This depends on the configuration for the proxy. Read the rest of this entry »