thanks, it works properly I appreciate your knowledge. So I am still a novice.

I got rid of confusion and YOU was the reason, it works properly, so I am still novice.

namespace NecRoutines
{
public class Invoke
{
private System.Windows.Forms.Timer TrzTimer = new System.Windows.Forms.Timer();
private void TrzInitialize()
{
this.TrzTimer.Tick += new System.EventHandler(this.TrzTimer_Tick);
TrzTimer.Interval = 1000;
TrzTimer.Enabled = true;
TrzTimer.Start();
}
private void TrzTimer_Tick(object sender, EventArgs e)
{
// do something when time elapses
}

public static void TrzStart()
{
   TrzInitialize();
}

}
}

   //An object reference is required for the non-static field, method, or property

this is the error message that i get for calling TrzInitialize() during building this DLL program. Consider that TrzInitialize() must be non static because of timer routine definition and TrzStart() must be static to be known for main program. thanks

You are right, assume that a program wants to check out a printer driver is loaded or not?

As I mentioned before, FrameWork was just an example. In general, how is it possible to check that a dll which is not even famous, is running or not?

FrameWork was just an example.

How can we detect from our program that a prerequired program such as dotNetFrameWork3 or 4 is installed and also is active now or not? thanks

float Width = 47;
textBox1.Text = System.Convert.ToString(Width);

Consider above statements. after executing this command the content of textBox1.Text will be 46.99 instead of 47; I've solved this problem by some functions, but I want to see is there any tuning in C# 2010 that I missed it? thanks

how can we detect from inside of our own program that internet connection is now active or not?

simply save the pre value and return it in case of pressing exit buttom.

[DllImport("kernel32.dll", EntryPoint = "SetSystemTime", SetLastError = true)]
public extern static bool Win32SetSystemTime(ref SystemTime sysTime);

By the above code I can change the system date of many version of MicroSoft Windows 7, but doesn't work on all of them. Do I miss something?

U are right, I did not think about it in this way.

In fact I want to disable internet for awhile to prevent spyware to access that sensitive portion of program which contains some personal information which is not coded yet. for example account number which is coming from keyboard.

How can we disable and enable the internet from inside of our program?

I appreciate your knowledge. It works properly. thanks

How can we Change the date of system (computer ) from inside of our own program?

Thanks, but I didn't need barcode generator, the thing that I need is a program (for example an ActiveX or DLL) which I be able to use them in my own project. I will search more carefully through the second link which u sent. :)

thanks :) I took a look at that link. I think it may work, but as I understand it can generate only one format (Code 39). thus user cant select his own standard. but it will give me good idea.

Hello and thanks :) for these links, but as u mentioned they don't work properly, I don't want to make my own barcode, I need a profesional OCX to use it in my project. I've found some of them, but they dont work on all kind of printers.

Is ther any component or OCX which we can use it to generate and print a barcode? when we use the one printer's facility, it doesn't work correctly for other printers. I want also to know is there a general software for this purpose? thanks