Using RegEx to validate an ip-address

[moster67]

Anyone who knows which pattern to use to validate an ip-address?

such as:

192.168.1.83

Thanks.

 

[Erel]

Here:

Sub Activity_Create(FirstTime As Boolean)
   Log(IsValidIp("192.168.1.83"))
   Log(IsValidIp("192.168.2221.83"))
End Sub

Sub IsValidIp(ip As String) As Boolean
   Dim m As Matcher
   m = Regex.Matcher("^(\d+)\.(\d+)\.(\d+)\.(\d+)$", ip)
   If m.Find = False Then Return False
   For i = 1 To 4
      If m.Group(i) > 255 OR m.Group(i) < 0 Then Return False
   Next
   Return True
End Sub

As you see I combine RegEx with some code. It is much easier to validate it this way.

 

[moster67]

Thanks once again Erel for your incredible support. :sign0188:

I tested it with a few scenarios (wrong and strange user-inputs) and it works very nice.

 

[TomasRiker]

Hi!

Actually you don't have to check for "< 0", because there can't be a minus sign. \d only matches the digits 0 through 9.

Also, it is possible to do the "< 256" check in the regex.
It gets a bit more complex then, but well possible:

(([01]?\d\d?|2[0-4]\d|25[0-5])\.){3}([01]?\d\d?|2[0-4]\d|25[0-5])

This is from my article about IP address matching with regular expressions.
( regex-for.com/ip-addresses/ )

 

[Erel]

Also, it is possible to do the "< 256" check in the regex.

This doesn't mean that there is any advantage with doing it with regex. Regex is a tool not a purpose.

 

[Jost aus Soest]

(([01]?\d\d?|2[0-4]\d|25[0-5])\.){3}([01]?\d\d?|2[0-4]\d|25[0-5])

That's nice and still readably! :sign0098: