TextBox allows only Character as first letter in windows application using vb.net

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Hi Friends , I have requirement on validations in windows application. Textbox allows only characters as first letter .

please any one help me.

Posted 26-Aug-13 19:49pm

CH Guravaiah

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Sauradipta Chaudhury 27-Aug-13 2:09am

By characters do you mean only Alphabets?

Sergey Alexandrovich Kryukov 27-Aug-13 2:25am

It makes no sense at all, but probably just because you are using wrong terminology. Anything you enter in a text box is "characters".
What do you mean, exactly?
—SA

2 solutions

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Sauradipta Chaudhury · Answer 1 · 2013-08-26T21:28:00

Try adding this eventhandler to your TextBox and see if that helps. I am assuming that you want the first character in the textbox as an alphabet i.e. either a-z or A-Z.

VB

Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
    Dim textBox As TextBox
    textBox = sender

    If (textBox.Text.Length > 0 And textBox.Text.Length = 1) Then
        Dim firstChar() As Char
        Dim ascii As Integer
        Dim isAlphabet As Boolean

        firstChar = textBox.Text.ToCharArray
        ascii = Convert.ToInt32(firstChar(0))

        If ((ascii <= 90 And ascii >= 65) Or (ascii <= 122 And ascii >= 97)) Then
            isAlphabet = True
        End If

        If (Not isAlphabet) Then
            TextBox1.Text = String.Empty
        End If
    End If

End Sub

0bsidian · Answer 2 · 2013-08-27T03:00:00

what about Regular Expressions?

Try this code, it will check if the text in your textbox matches the pattern in the []-brackets (^ will check the first character, A-Z will only allow uppercase characters):

VB

Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
    Dim textBox As TextBox
    textBox = sender

    If (textBox.Text.Length > 0 And textBox.Text.Length = 1) Then
       If Not Regex.IsMatch(textBox.Text, "^[A-Z]") then
          TextBox1.Text = String.Empty
       End If
    End If
End Sub

Remember to import the System.Text.RegularExpressions, otherwise the code won't work.

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TextBox allows only Character as first letter in windows application using vb.net

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TextBox allows only Character as first letter in windows application using vb.net

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