asked on

String Validation

Hi

How can I validate a string which only allows these characters... A - Z , a-z, if other than those characters are detected then I want to throw an exception.

Thanks
Sheldon

RonaldBiemans

if System.Text.RegularExpression.RegEx.IsMatch(yourstring, "[a-zA-Z]")
msgbox ("ok")
else
throw
End If

ASKER CERTIFIED SOLUTION

S-Twilley

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S-Twilley

oops, too slow there :P

Bob Learned

Actually, Steve, your expression will work, and Ronald's won't. The concept of looking for non-alpha characters is a better approach.

Bob

S-Twilley

I didn't even notice. Well, I'm sure the thought was there... easy slip-up for someone to make :P

RonaldBiemans

you are right TheLeanedOne (as usual :-)

but this should

If System.Text.RegularExpressions.Regex.IsMatch("aa1aaa", "^[a-zA-Z]+$") Then

Sheldonh

ASKER

Hi

I have combined your techniques to come up with this solution...the ones that you guys provided didn't work.

So, here is another question. What if I enter a person's name and there is a space...how would I accomodate the space?

Dim RegTest As New System.Text.RegularExpressions.Regex("[^a-zA-Z]")

If RegTest.IsMatch(TxtNames.Text) Then

MsgBox("Kak", MsgBoxStyle.Exclamation, "Message")

e.Cancel = True

Else

MsgBox("Success", MsgBoxStyle.Information, "Message")

S-Twilley

if you had a problem with mine... it's probably because you didn't add the import statement at the top of your class:

Imports System.Text.RegularExpressions

(I did mention it)

unless you didn't like the If Else Block

Sheldonh

ASKER

I see, your're probably right.

Well it is working now, I just need a little help with the spaces thing... no harm done... ;-)

S-Twilley

what spaces thing? :\

Sheldonh

ASKER

my comment with the code attached above...

S-Twilley

do you just want to allow one space within a valid string, or any number of spaces?

SOLUTION

Bob Learned

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Sheldonh

ASKER

any number of spaces

S-Twilley

Bob's regex should do it... and im not sure, but you might also want to check the length of Trim(myTestStr) to see if it's 0... which means that the entire string was full of spaces... so something like:

Dim regTest As New Regex("[^a-zA-Z\s]")

...

myTestStr = "kjhsdkg98797sdfd"

If regTest.Match(myTestStr).Success then
'contains bad chars
Else
If Trim(myTestStr).Length = 0 Then
'myTestStr was either empty, or just all spaces
Else
'myTestStr contains at least some letters, but possible spaces too
End If
End If

============

Give credit to Bob though, since he did provide the Regex for spaces before me

Bob Learned

Thanks, Steve, I just beat you to the punch. Must give credit where credit is due.

Bob

Sheldonh

ASKER

Thanks guys, you all helped alot.

Cheers
Sheldon