Start sub when textbox on my form is selected

You could do that best with javascript and the onfocus event:

<script language='JavaScript'>
function ClearText(id) {
   var textbox = document.getElementById(id);
   textbox.value = "";
}
</script>

<asp:TextBox id="sample" onfocus="ClearText('sample')"></asp:TextBox>

u want to do this in windows application or web?
If in windows app this will work. Use the enter event of textbox
Private Sub TextBox1_Enter(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.Enter
      Call validatetext()
End Sub
Sub validatetext()
      TextBox1.Text = ""
      MessageBox.Show("Enter valid data")
End Sub

Cheers!!
Happy programming

hi sreeganesh,
it is a web application (forgot to tell you) and the .enter event is not allowed there


existenz2,
it must be coded in behind code, a lot of other programming must be placed around it

I think this code will suit ur need.
I was not sure wht type off app. thts y given the previous code. Could u try this.
private void Page_Load(object sender, System.EventArgs e)
{
      // Put user code to initialize the page here
      txtTest.Attributes.Add("onFocus","ClearTextbox()");
      StringBuilder sb = new StringBuilder();
      sb.Append("<script language=\"javascript\">\n");
      sb.Append("function ClearTextbox() {\n");
      sb.AppendFormat("eval(\"document.forms[0].{0}.value = \\'\\'\");\n", tTest.ClientID);
      sb.Append("alert('Enter a valid data');}\n");
      sb.Append("</script>");
      Page.RegisterClientScriptBlock("ClearTextbox",sb.ToString());

}

Small correction
sb.AppendFormat("eval(\"document.forms[0].{0}.value = \\'\\'\");\n", tTest.ClientID);
In this line instead of tTest.ClientId
use
txtTest.Client ID

Also include
System.Text namespace

sreeganesh
it is a vb.net application

OK  VB.NET WEB APPLICATION
Here goes the code try it

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            txtTest.Attributes.Add("onFocus", "ClearTextbox();")
            Dim sb As New StringBuilder
            'StringBuilder sb = new StringBuilder();
            sb.Append("<script language=javascript> ")
            sb.Append("function ClearTextbox() { ")
            sb.AppendFormat("eval(document.forms[0].{0}.value =' '); ", txtTest.ClientID)
            sb.Append("alert('Enter a valid data');} ")
            sb.Append("</script>")
            Page.RegisterClientScriptBlock("ClearTextbox", sb.ToString())
End Sub

Hope this will suit ur need
Cheers!!
Happy programming

sreeganesh
the code works but the alert must not appear

is there a possibility to start the clear just when the textbox is hit without that alert message
tks

Ok thts simple just remove the line having alert from the javascript code ie
Try the below code

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            txtTest.Attributes.Add("onFocus", "ClearTextbox();")
            Dim sb As New StringBuilder
            'StringBuilder sb = new StringBuilder();
            sb.Append("<script language=javascript> ")
            sb.Append("function ClearTextbox() { ")
            sb.AppendFormat("eval(document.forms[0].{0}.value =' '); ", txtTest.ClientID)
            sb.Append("</script>")
            Page.RegisterClientScriptBlock("ClearTextbox", sb.ToString())
End Sub

sreeganesh
i have put the changed code
but now nothing is happening
in the previous code, the text became empty

all right !
that s the way i like it    ehe ehe
tks