by Chris Morton (5 Submissions)
Category: String Manipulation
Compatability: VB.NET
Difficulty: Unknown Difficulty
Originally Published: Fri 10th June 2005
Date Added: Mon 8th February 2021
Rating: 
(1 Votes)
Function Validates IP address returns boolean
VBcoders
Dim count As Byte
Dim dotcount As Byte
'check for illegal charaters
For count = 1 To Len(IPAddress)
If InStr("1234567890.", LCase(Mid(IPAddress, count, 1))) > 0 Then
Else
MsgBox("There are illegal characters")
Return False
End If
Next
'check if first character is "."
If InStr(IPAddress, ".") = 1 Then
MsgBox("First Character is '.'")
Return False
End If
'check if there are consecutive ".."
If InStr(IPAddress, "..") > 0 Then
MsgBox("There are consecutive '.'")
Return False
End If
'check for number of dots
For count = 1 To Len(IPAddress)
If Mid(IPAddress, count, 1) = "." Then
dotcount += 1
If dotcount > 3 Then
MsgBox("There are two many '.'")
Return False
End If
End If
Next
'check for values of ip address components
Dim num() = Split(IPAddress, ".")
For count = 0 To 3
If (num(count)) > 255 Then
MsgBox("IP address is invalid")
Return False
End If
'checks if last split is = 255
If num(3) = 255 Then
MsgBox("IP address is invalid")
Return False
End If
Next
MsgBox("Valid IP address")
Return True
'if all of these things are true return true
End Function
