How to paste only valid value in textbox.

S a n d y

Hi All, I want to paste only valid value(like numeric value) in textbox through mouse(right click) and keyboard(Ctrl+V). Thanks in advance.

Nagy Vilmos

Have you tried anything yet?

Panic, Chaos, Destruction. My work here is done.

S a n d y

No, I do not understand how to do it?

N a v a n e e t h

Check this[^]

Navaneeth How to use google | Ask smart questions

Vikram A Punathambekar

Handle the TextChanged event. Even better, use a NumericUpDown control.

Cheers, Vıkram.

"You idiot British surprise me that your generators which grew up after Mid 50s had no brain at all." - Adnan Siddiqi.

DaveyM69

override WndProc, trap WM_PASTE and process there. Check out pinvoke.net.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

S a n d y

Thanks, but I don't know how to use this. Please give me a little example.

Vengatachalapathy Palanivel

If that's a web application or windows application . If it's a web application, then you can go about by Javascripts.

DaveyM69

OK. This example creates a customized TextBox so add this class, build then drop onto a form.

public class RestrictedTextBox : TextBox
{
    private const int WM\_PASTE = 0x0302;

    protected override void WndProc(ref Message m)
    {
        if (m.Msg == WM\_PASTE)
        {
            if (!IsPasteValid())
            {
                m.Result = IntPtr.Zero;
                return;
            }
        }
        base.WndProc(ref m);
    }

    private bool IsPasteValid()
    {
        bool rtn = false;
        IDataObject obj = Clipboard.GetDataObject();
        string pasteString = (string)obj.GetData(typeof(string));
        // Do checks on pasteString here and set rtn to true if OK.
        return rtn;
    }
}

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

S a n d y

Its Window application.

S a n d y

Thanks

Vengatachalapathy Palanivel

I think, this piece of code will help you out...

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if ( Convert.ToInt16(e.KeyChar) >= 48 && Convert.ToInt16(e.KeyChar) <=57)
{
e.KeyChar = e.KeyChar;
}
else
{
e.KeyChar = Convert.ToChar(0);
}
}

    private void textBox1\_TextChanged(object sender, EventArgs e)
    {
        char\[\] strSample = new char\[((System.Windows.Forms.TextBox)(sender)).Text.ToString().Length\];

        strSample = (((System.Windows.Forms.TextBox)(sender)).Text).ToCharArray();

        for (int i=0; i<strSample.Length;i++)
        {
            if (Convert.ToInt16(strSample\[i\]) >= 48 && Convert.ToInt16(strSample\[i\]) <= 57)
            {
                continue;
            }
            else
            {
                ((System.Windows.Forms.TextBox)(sender)).Text = "";
                break;
            }
        }
        
    }

Try this and let me know if you have any concerns. Regards, Vengat P

S a n d y

Thanks Vengat, Everything is worked fine but if we paste characters then textbox goes blank. In that case we want current value of textbox. Then how to do that.

Vengatachalapathy Palanivel

I am also new to windows application, but i'm sure that, you can bind the value of textbox again with the help of a global variable(that will be updated for each key press event and text change event). Sample: private string strTestVal = string.Empty; on keypress event: in if condition strTestVal = textBox1.Text.ToString(); on text change event: textBox1.Text = strTestVal;

Regards, Vengat P