How to allow backspace and space when validating letters in VB?

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I have tried everything and I'm still not able to press backspace and space when entering the relevant data (letters) into the textbox.

What I have tried:

If Asc(e.KeyChar) < 65 Or Asc(e.KeyChar) < 90 _

And Asc(e.KeyChar) < 97 Or Asc(e.KeyChar) > 122 Then

MessageBox.Show("Please enter letters only")

e.Handled = True

End If

Posted 21-Dec-17 0:11am

faiqaa

Updated 21-Dec-17 0:32am

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Comments

Makhno Khan Pitafi 1-Nov-23 6:40am

How to code backspace in vb

2 solutions

Solution 2

Look at your code:

VB

If Asc(e.KeyChar) < 65 Or Asc(e.KeyChar) < 90 _
And Asc(e.KeyChar) < 97 Or Asc(e.KeyChar) > 122 Then

If it's below 65, it's below 90.
And what's the precedence of And and Or? Is it evaluated as

(a Or b) And (c Or d)

Or as

a Or (b And c) Or d

Try this:

VB

If Char.IsLetterOrDigit(e.KeyChar) OrElse e.KeyChar = " "c OrElse e.KeyChar = CChar(Keys.Back) Then
        ' All OK.
    Else
        MessageBox.Show("Please enter letters only")
        e.Handled = True
    End If

Posted 21-Dec-17 0:32am

OriginalGriff

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A_Griffin · Accepted Answer · 2017-12-21T00:24:00

Solution 1

Use a Select Case

VB

Select Case Asc(e.KeyChar)
  Case 8, 32, 65 To 90, 97 To 122
     ' allowed
     ' add other blocks as required - eg 48 to 57 to allow numbers

  Case Else  
     MessageBox.Show("Please enter letters only")
End Select

ASCII Tables[^]

Posted 21-Dec-17 0:24am

A_Griffin

Updated 21-Dec-17 0:25am

v2