How to Validate Textbox

How to validate the textbox?If empty return error message

VB Code:

If TextboxName.text = "" Then
     MessageBox.Show("Please enter something")
End If

Code:

---


if textbox1.text="" then
msgbox("invalid")
end if

---

it's a good idea to put the focus back on the textbox, and also you need those code in the Validated event of your textbox. Use the Trim function to remove empty space also (so if they enter " " it would be considered "")

VB Code:

Private Sub TextBox1_Validated(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.Validated
        If TextBox1.Text.Trim = "" Then
            TextBox1.Focus()
            MessageBox.Show("Boo!")
        End If
    End Sub

If want to validate more than 1 text box can i include inside the sub procedure?

VB Code:

Private Sub txt_Validated(ByVal sender As Object, ByVal e As System.EventArgs) Handles [u]TextBox1.Validated, TextBox2.Validated, TextBox3.Validated[/u]
        Dim t As TextBox = CType(sender, TextBox)
        If t.Text = "" Then
            t.Focus()
            MessageBox.Show("Boo!")
        End If
    End Sub

Just an addition to the not polite guy. :bigyello:

Hi,

I didn't understand this part
Dim t As TextBox = CType(sender, TextBox)

Thank You

sender object (the one who sends a message to the event) is casted to it's TextBox form. Then pass the instance to t which of type TextBox. Then we can manipulate t, ie. display the TextBox's Name property or Tag, etc.

Hi,

Private Sub txt_Validated(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.Validated, TextBox2.Validated, TextBox3.Validated
Dim t As TextBox = CType(sender, TextBox)
If t.Text = "" Then
t.Focus()
MessageBox.Show("Boo!")
End If
End Sub

This code just validates only the first field

Hi,

Private Sub txt_Validated(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.Validated, TextBox2.Validated, TextBox3.Validated
Dim t As TextBox = CType(sender, TextBox)
If t.Text = "" Then
t.Focus()
MessageBox.Show("Boo!")
End If
End Sub

This code just validates only the first field

Hi,

The it depends on what you want to validate. If you want to check each keypress for a valid number see the codebank

http://www.vbforums.com/showthread.php?t=314936

If you want to check for something other than numerics you should be able to adapt that code.