by RajeswaraRao Gangina (1 Submission)
Category: String Manipulation
Compatability: Visual Basic 5.0
Difficulty: Unknown Difficulty
Originally Published: Tue 10th April 2001
Date Added: Mon 8th February 2021
Rating: 
(1 Votes)
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VBcoders
Dim iTemp As Integer
Select Case KeyAscii
Case 8 'ASCII value of Back Space =8
' Back space is allowed at any time
Exit Sub
Case Asc("@") ' @ is allowed only if there are some characters in the textbox
If TextBox.SelStart = 0 Then
KeyAscii = 0
ElseIf InStr(1, TextBox, "@") > 0 Then
KeyAscii = 0
End If
Exit Sub
Case Asc(".") ' . is allowed only after printing @
iTemp = InStr(1, TextBox, "@")
If (iTemp = 0) Or (iTemp >= TextBox.SelStart) Then
KeyAscii = 0
Exit Sub
ElseIf TextBox.SelStart = 0 Then
KeyAscii = 0
Exit Sub
ElseIf Mid(TextBox, TextBox.SelStart, 1) = "." Then
KeyAscii = 0
Exit Sub
End If
Exit Sub
Case Asc("_") ' _ is allowed only before printing @
iTemp = InStr(1, TextBox, "@")
If (iTemp > 0) And (iTemp < TextBox.SelStart) Then
KeyAscii = 0
End If
Exit Sub
End Select
If Not ((KeyAscii >= Asc("0") And KeyAscii <= Asc("9")) Or (KeyAscii >= Asc("a") And KeyAscii <= Asc("z")) Or (KeyAscii >= Asc("A") And KeyAscii <= Asc("Z"))) Then
KeyAscii = 0
Exit Sub
End If
