Need help with regex

  • Thread starter Thread starter Michael R. Pierotti
  • Start date Start date
M

Michael R. Pierotti

Dim reg As New Regex("^\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}$")
Dim m As Match = reg.Match(txtIPAddress.Text)
If m.Success Then
'No need to do anything here
Else
MessageBox.Show("You need to enter a valid IP Address", "Error!",
MessageBoxButtons.OK, MessageBoxIcon.Hand)
txtIPAddress.Focus()
Return
End If




I need to match a IP addy on this and I would think this should match only a
x.x.x.x to xxx.xxx.xxx.xxx pattern yet it passes as a match when I input
192168121113

Any ideas what I am doing wrong here ?

Thanks,

Mike
 
Michael,
"." matches any character except \n. To match a period you need to "escape"
it with a slash. "\." will match a period.

Try the following:

Const pattern As String = "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$"
Static reg As New Regex(pattern, RegexOptions.Compiled)
Dim m As Match = reg.Match(txtIPAddress.Text)
If m.Success Then
'No need to do anything here
Else
MessageBox.Show("You need to enter a valid IP Address",
"Error!", MessageBoxButtons.OK, MessageBoxIcon.Hand)
End If

Unless I need the Match object specifically, I normally use Regex.IsMatch
instead.

Something like:
Const pattern As String = "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$"
Static reg As New Regex(pattern, RegexOptions.Compiled)
If reg.IsMatch(txtIPAddress.Text) Then
'No need to do anything here
Else
MessageBox.Show("You need to enter a valid IP Address",
"Error!", MessageBoxButtons.OK, MessageBoxIcon.Hand)
End If

Hope this helps
Jay
 
Thank mate how did I miss that ? LOL

Jay B. Harlow said:
Michael,
"." matches any character except \n. To match a period you need to "escape"
it with a slash. "\." will match a period.

Try the following:

Const pattern As String = "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$"
Static reg As New Regex(pattern, RegexOptions.Compiled)
Dim m As Match = reg.Match(txtIPAddress.Text)
If m.Success Then
'No need to do anything here
Else
MessageBox.Show("You need to enter a valid IP Address",
"Error!", MessageBoxButtons.OK, MessageBoxIcon.Hand)
End If

Unless I need the Match object specifically, I normally use Regex.IsMatch
instead.

Something like:
Const pattern As String = "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$"
Static reg As New Regex(pattern, RegexOptions.Compiled)
If reg.IsMatch(txtIPAddress.Text) Then
'No need to do anything here
Else
MessageBox.Show("You need to enter a valid IP Address",
"Error!", MessageBoxButtons.OK, MessageBoxIcon.Hand)
End If

Hope this helps
Jay
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