How to allow backspace and space when validating letters?

Question

The code I am using is this:

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

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

Are you sure this is correct: `Or Asc(e.KeyChar) < 90`? Didn't you mean to check if it was _**greater**_ than 90? — Visual Vincent, Dec 21 '17 at 12:07
Yes, a key element of any good UI is to scold and punish the user for every erroneous keystroke. No typos allowed. — Ňɏssa Pøngjǣrdenlarp, Dec 21 '17 at 19:17

Lajos Arpad · Answer 1 · 2017-12-21T12:17:32.957

3

Character code for backspace is 8 and for space is 32, so your code should be:

If (Asc(e.KeyChar) < 65 OrElse Asc(e.KeyChar) < 90) _
AndAlso (Asc(e.KeyChar) < 97 OrElse Asc(e.KeyChar) > 122) _
AndAlso Asc(e.KeyChar) <> 8 AndAlso Asc(e.KeyChar) <> 32 Then
    MessageBox.Show("Please enter letters only")
    e.Handled = True
End If

Note that I used AndAlso, to stop the evaluation when the first False is encountered.

edited Dec 21 '17 at 12:17

answered Dec 21 '17 at 11:26

Lajos Arpad

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2

Since you switched to `AndAlso` you might want to use [**`OrElse`**](https://stackoverflow.com/q/8409467) as well ;). Also, consider grouping the `Or/OrElse` checks with brackets. That way it is easier to read, but you also ensure that it executes correctly. – Visual Vincent Dec 21 '17 at 12:02

How to allow backspace and space when validating letters?

1 Answers1