WPF FAQ
Questions and answers in this FAQ have been collected from newsgroup posts, various mailing lists and the employees of Syncfusion.

32. TextBox

 FAQ Home
   32.1 How to cast the value entered in a textbox to integer?
   32.2 How to allow only numeric values in a textbox using ASP.NET Validator control?
   32.3 Why does TextBox retain its values when posting in spite of having ViewState property disabled for TextBox,?
   32.4 I am running the query SQL="Select name from profile where proID=1"; and I am getting the result in Dataset dsdata. How can I read the text from the dataset and assign it to textbox1.text ?
   32.5 Why do I get error message "Option Strict On disallows implicit conversions from 'System.Web.UI.Control' to 'System.Web.UI.WebControls.TextBox'."?
   32.6 How to align the Text property of the Textbox Control?
   32.7 How to clear all the textboxes in my form?
   32.8 How to convert TextBox value into a DateTime variable?
   32.9 How to programmatically set the width of the textbox control?
   32.10 How to get the textbox value at the client side ?
   32.11 How to display data in Textboxes using DataSet?
   32.12 How to display data in Textboxes using DataReader?
   32.13 Is there a TextArea in ASP.NET?
   32.14 How to right align the text in the TextBox?
   32.15 How to force the max no. of characters in a multiline TextBox using RegularExpressionValidator?
   32.16 How to change server control backcolor from a variable?
   32.17 How to create an array of Web Controls?
   32.18 How to show TextBox web server control with TextMode Property Password as **** rather than blank?



32.1 How to cast the value entered in a textbox to integer?

VB.NET


Int32.Parse(TextBox1.Text)


C#


Int32.Parse(TextBox1.Text);



32.2 How to allow only numeric values in a textbox using ASP.NET Validator control?


<asp:TextBox id="txtNumber" Runat="server" />
<asp:RegularExpressionValidator ID="vldNumber" ControlToValidate="txtNumber" Display="Dynamic" ErrorMessage="Not a number" ValidationExpression="(^([0-9]*|\d*\d{1}?\d*)$)" Runat="server">
</asp:RegularExpressionValidator>




32.3 Why does TextBox retain its values when posting in spite of having ViewState property disabled for TextBox,?

Refer to the link ASP.NET: TextBox and EnableViewState="False"

32.4 I am running the query SQL="Select name from profile where proID=1"; and I am getting the result in Dataset dsdata. How can I read the text from the dataset and assign it to textbox1.text ?

VB.NET


Textbox1.Text= dsData.Tables(0).Rows(0)("FieldName").ToString()


C#


TextBox1.Text=dsData.Tables[0].Rows[0]["FieldName"].ToString();



32.5 Why do I get error message "Option Strict On disallows implicit conversions from 'System.Web.UI.Control' to 'System.Web.UI.WebControls.TextBox'."?

For type Casting apply the following steps

VB.NET


dim aprtxt as string
aprtxt= CType(e.Item.FindControl("txtapr"), TextBox)


C#


string aprtxt;
aprtxt = (TextBox) e.Item.FindControl["txtapr"];



32.6 How to align the Text property of the Textbox Control?

VB.NET


TextBox1.Style("text-align")="right"


C#


TextBox1.Style["text-align"]="right";



32.7 How to clear all the textboxes in my form?

VB.NET


Dim ctl As Control
For Each ctl In Page.Controls(1).Controls
If TypeOf ctl Is TextBox Then
CType(ctl, TextBox).Text = ""
End If
Next


C#


foreach (Control ctl in Page.Controls[1].Controls )
{
     TextBox tb = ctl as TextBox;
     if (tb!=null)
     {
     tb.Text = "" ;
     }
}


Note: Page.Controls[1]=> control is within the

tag


32.8 How to convert TextBox value into a DateTime variable?

VB.NET


Dim dt As DateTime = DateTime.Parse(TextBox1.Text)


C#


DateTime dt = DateTime.Parse(TextBox1.Text);


By default Date.Parse check the date as MDY format Refer DateTime.Parse for a specified Date Format.

32.9 How to programmatically set the width of the textbox control?

VB.NET


TextBox1.Width = Unit.Pixel(100)


C#


TextBox1.Width = Unit.Pixel(100);



32.10 How to get the textbox value at the client side ?


<script lang="javascript">
function CheckFunction()
{
if (document.getElementById('<%=textbox2.ClientID%>').value == "")
{
     alert("Please enter a value");
     return;
}
}
</script>



<asp:textbox id="textbox2" runat="Server"></asp:textbox>
<input type=button id="btn1" onclick="javascript:CheckFunction();" value="Click">




32.11 How to display data in Textboxes using DataSet?


Product ID : <asp:TextBox id="TextBox1" style="Z-INDEX: 101; LEFT: 80px; POSITION: absolute; TOP: 64px" runat="server"></asp:TextBox>
Product Name:<asp:TextBox id="TextBox2" style="Z-INDEX: 102; LEFT: 80px; POSITION: absolute; TOP: 112px" runat="server"></asp:TextBox>


VB.NET


'Populate the DataSet
'...

'Display in TextBoxes using Column Name
TextBox1.Text = ds.Tables (0).Rows(0)("ProductId").ToString ();
TextBox2.Text =ds.Tables (0).Rows(0)("ProductName").ToString ();

'Display in TextBoxes using Column Index
TextBox1.Text = ds.Tables (0).Rows(0)(0).ToString ();
TextBox2.Text =ds.Tables (0).Rows(0)(1).ToString ();


C#


//Populate the DataSet
//...

//Display in TextBoxes using Column Name
TextBox1.Text = ds.Tables [0].Rows[0]["ProductId"].ToString ();
TextBox2.Text =ds.Tables [0].Rows[0]["ProductName"].ToString ();

//Display in TextBoxes using Column Index
TextBox1.Text = ds.Tables [0].Rows[0][0].ToString ();
TextBox2.Text =ds.Tables [0].Rows[0][1].ToString ();




32.12 How to display data in Textboxes using DataReader?


Id : <asp:TextBox id="TextBox1" style="Z-INDEX: 102; LEFT: 128px; POSITION: absolute; TOP: 32px" runat="server"></asp:TextBox>
Name : <asp:TextBox id="TextBox2" style="Z-INDEX: 103; LEFT: 128px; POSITION: absolute; TOP: 72px" runat="server"></asp:TextBox>


VB.NET


Dim cn As SqlConnection
Dim cmd As SqlCommand
Dim rdr As SqlDataReader

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
     ' Put user code to initialize the page here
     Try
          cn = New SqlConnection("server=localhost;uid=sa;pwd=;database=northwind")
          cmd = New SqlCommand("select * from Products where productid =1", cn)
          cn.Open()
          rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection)
          rdr.Read()
          TextBox1.Text = rdr("ProductId").ToString()
          TextBox2.Text = rdr("ProductName").ToString()
     Catch ex As Exception
          Response.Write(ex.Message.ToString())
     Finally
          rdr.Close()
          cn.Close()
     End Try
End Sub


C#


SqlConnection cn ;
SqlCommand cmd ;
SqlDataReader rdr ;
private void Page_Load(object sender, System.EventArgs e)
{
     // Put user code to initialize the page here
     try
     {
          cn = new SqlConnection("server=localhost;uid=sa;pwd=;database=northwind");
          cmd = new SqlCommand( "select * from Products where productid=1 ", cn);
          cn.Open();
          rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection );
          rdr.Read ();
          TextBox1.Text =rdr["ProductId"].ToString ();
          TextBox2.Text =rdr["ProductName"].ToString ();
     }
     catch (Exception ex)
     {
          Response.Write (ex.Message.ToString ());
     }
     finally
     {
          rdr.Close();
          cn.Close();
     }
}



32.13 Is there a TextArea in ASP.NET?

You can use the TextBox webserver control and set the TextMode = MultiLine

32.14 How to right align the text in the TextBox?


<asp:TextBox id="TextBox1" dir=rtl runat="server"></asp:TextBox>



32.15 How to force the max no. of characters in a multiline TextBox using RegularExpressionValidator?


<asp:TextBox id="TextBox1" style="Z-INDEX: 101; LEFT: 0px; POSITION: absolute; TOP: 112px" runat="server" TextMode="MultiLine"></asp:TextBox>
<asp:RegularExpressionValidator id="RegularExpressionValidator1" style="Z-INDEX: 102; LEFT: 216px; POSITION: absolute; TOP: 112px"
     runat="server" ErrorMessage="MaxLength is 20" ControlToValidate="TextBox1"      ValidationExpression="^\w{1,20}$">
</asp:RegularExpressionValidator>




32.16 How to change server control backcolor from a variable?


<asp:TextBox id="TextBox1" BackColor =<%#colCon.ConvertFromString(bgcolor)%> runat="server">
</asp:TextBox>


VB.NET


Protected colCon As New System.Drawing.ColorConverter
Protected bgcolor As String = "#556600"

'In Page_Load
Page.DataBind()


C#


protected System.Drawing.ColorConverter colCon =new System.Drawing.ColorConverter();
protected string bgcolor = "#556600";

//In Page_Load
Page.Databind();



32.17 How to create an array of Web Controls?


<asp:PlaceHolder id="PlaceHolder1" runat="server"></asp:PlaceHolder>


VB.NET


Dim textboxes(5) As TextBox
Dim i As Integer
For i = 0 To 4
     textboxes(i) = New TextBox()
     textboxes(i).ID = "TextBox" + i
     textboxes(i).AutoPostBack = True
     PlaceHolder1.Controls.Add(textboxes(i))
Next


C#


TextBox[] textboxes = new TextBox[5];
for (int i=0; i<5; i++)
{
     textboxes[i] = new TextBox();
     textboxes[i].ID = "TextBox" + i;
     textboxes[i].AutoPostBack = true;
     PlaceHolder1.Controls.Add(textboxes[i]);
}



32.18 How to show TextBox web server control with TextMode Property Password as **** rather than blank?

For security reason, TextBox with TextMode="Password" setting cannot be assigned or populated via the Text property on Page_Load or PostBack event.

It's not recommend for to prefill a "Password" type TextBox with the("***") characters, though below is the solution to achieve this.

VB.NET


ViewState("Pwd")=TextBox1.Text ;
TextBox1.Attributes.Add("value", ViewState("Pwd").ToString ()) ;


C#


ViewState["Pwd"]=TextBox1.Text ;
TextBox1.Attributes.Add("value", ViewState["Pwd"].ToString ()) ;


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