Having problem on listbox with an argument

[dr_iton]

I created a software in Windows Form Application that includes two Forms.
In the form1 there are some textboxes and a listbox.
One of textboxes i populated in a listbox with followin method.
the name of textbox is xhirollogariaBox

             Random rasti = new Random();
            int numri = rasti.Next(10000000, 99999999);
            xhiro = "1301" + numri;
            xhirollogariaBox.Text = Convert.ToString(xhiro); 

The problem is that i don't know how to make a method or a solution to prevent the future number not to be thw same as they are in thelistbox.
So how to make a solution to prevent next entries (numbers) to be writen if the same number already exists in the listbox.

Also one other problem is that I don't know how to prevent another textbox to include numbers, probably that is something like regular expressions or whatever.

Thank you in advance for your reply.

[deceptikon]

Well, an obvious first attempt is to loop through the items in the listbox and not update your textbox if the random number already exists:

xhiro = "1301" + numri;

bool exists = false;

foreach (var item in listbox.Items)
{
    if (item == xhiro)
    {
        exists = true;
        break;
    }
}

if (!exists)
    xhirollogariaBox.Text = Convert.ToString(xhiro);

Also one other problem is that I don't know how to prevent another textbox to include numbers, probably that is something like regular expressions or whatever.

If you only want to allow numbers then a numericupdown control makes more sense. But a quick and dirty solution for regular textboxes is simply ignoring non-numeric digits in the KeyPress event:

private void textBox_KeyPress(object sender, KeyPressEventArgs e)
{
    e.Handled = !char.IsDigit(e.KeyChar);
}

[dr_iton]

Thank you very much for your reply, honestly i dod fixed the problem, but I can't fix the following one:

 public void bilanci()
        {
            double vlera = 0;

            foreach (string stringu in GjendjaListBox.Items)
            {
                vlera = vlera + Convert.ToDouble(stringu.Split('\t')[4]);
            }
            this.GjendjaButon.Text = "Gjendja: " + vlera;
        }

How to make this to not accept values less than zero. With other words if I press a button to draw a value that this "vlera" amount goes to minus values.
If I press Add buton I can increase the value of "vlera", if a press draw button I can decrease the value of "vlera".
How to make this to not draw values less than zero.
Cheers

[deceptikon]

Well, the ideal solution would be to disallow negative values in the first place, but a quick fix would be to take the absolute value of vlera so that it's never negative:

GjendjaButon.Text = "Gjendja: " + Math.Abs(vlera);

[dr_iton]

I'm writing the text in a text file using following method:

 string data = Convert.ToString(DateTime.Now);
                StreamWriter swGjendja = new StreamWriter(caku, true);
                swGjendja.WriteLine(data + "\t" + emriBox.Text + "\t"
                                    + mbiemriBox.Text + "\t"
                                    + xhirollogariaBox.Text + "\t-"
                                    + vleraBox.Text + "\t"
                                    + "Terheqje");
                swGjendja.Close();
                LexoGjendjenFajll();
                bilanci();

Also I'm reading from file with this method:

public void LexoGjendjenFajll()
         {
            GjendjaListBox.Items.Clear();
            List<string> linja = new List<string>();

            string strLinja = "";
            StreamReader srGjendjen = new StreamReader(caku, true);
            try
            {
                while ((strLinja = srGjendjen.ReadLine()) != null)
                {
                    //Paraqitja e shenimeve për personin e caktuar
                    if (strLinja.Split('\t')[1] == this.emriBox.Text && strLinja.Split('\t')[2] == 
                        this.mbiemriBox.Text && strLinja.Split('\t')[3] == this.xhirollogariaBox.Text)
                    {
                        GjendjaListBox.Items.Add(strLinja);
                    }
                }
                srGjendjen.Close();
            }
            catch
            { }
        }

I think that the solution must be different as you gave me.
Cheers

[deceptikon]

I think that the solution must be different as you gave me.

Sorry dude, but you keep showing me different code as an example of your problem. At this point I have no clue what you want.

[dr_iton]

All I want to say is if you want to draw an amount from "vlera" that the result is a negative value, you could not be able to draw that amount.
The Math.abs is not a solution, because the negative values converts to positive ones. So is there a way to say that if the result is less than zero, to recieve a message that you can not draw that amount because you dont have credits (just like in prepaid SIM cards).

[deceptikon]

So is there a way to say that if the result is less than zero, to recieve a message that you can not draw that amount because you dont have credits (just like in prepaid SIM cards).

Yes. Check the value and put up a message if someone tries to draw more from an account than the current balance. This is what I meant originally by saying "the ideal solution would be to disallow negative values in the first place".

[tinstaafl]

You could use Math.Sign(value) if the return does not equal 1 make the value 0.

[dr_iton]

I still haven't found a solution with folloving:

  public void bilanci()
    {
        double vlera = 0;

            foreach (string stringu in GjendjaListBox.Items)
            {

            vlera = vlera + Convert.ToDouble(stringu.Split('\t')[4]);
            }
        this.GjendjaButon.Text = "Gjendja: " + vlera;
    }

Please give me a code.

[tinstaafl]

this might do it:

     public void bilanci()
    {
        double vlera = 0;
        foreach (string stringu in GjendjaListBox.Items)
        {
            vlera = vlera + Convert.ToDouble(stringu.Split('\t')[4]);
        }
        if(Math.Sign(vlera)<> 1)
        {
            vlera=0;
        }
        this.GjendjaButon.Text = "Gjendja: " + vlera;
    }

If vlera is a negative value or 0 then you can set it to 0, or you can show a messagebox with a message(MessageBox.Show("Not Enough Credit");.