VB: Add a space after a specific character into a string if it does not already have one - vb.net

Question

I want all of my strings to be formatted consistently. It is grabbing values from the database and sometimes there are not spaces after colons, but there should be. My goal is to add a space after a colon (:) if there isn't one already. I would prefer to do this without regex, but I am open to any solutions! Thanks so much.

Answer 1

Edit: Apologies I read the title as VBA, have updated now.
Here is a nice simple solution for you.
Replace everything with a Colon and a space with just a Colon meaning all Colons no longer have a space regardless of weather they did or not initially.
Then Replace all Colons with a Colon and a Space:
Dim value1 As String = "Hello:World"
value1 = value1.Replace(": ", ":").Replace(":", ": ")

Answer 2

I can't say it's the most elegant. And its performance is not optimized, though using String.IndexOf should in general be faster than looping over every character. But being a brute force solution, it sure doesn't use regex. ;)
Besides regex, I'm sure there's a cute one-line solution using LINQ, but it's probably hard to read and maintain. Someone is welcome to post that for comparison.
Option Strict On
Module Module1
Sub Main()
Console.WriteLine(EnsureSpaceAfterColon("first: second:asdf third::"))
'prints:
'"first: second: asdf third: : "
End Sub
Public Function EnsureSpaceAfterColon(input As String) As String
Dim colon As Char = CChar(":")
Dim space As Char = CChar(" ")
Dim returnString As String = String.Copy(input) 'leave the original alone
Dim index As Integer = input.IndexOf(colon)
While index > -1 'String.IndexOf returns -1 if the index is not found
'if the index is the last index, there is no space, so add it
'or else if the Char at the next index is not a space, make it so
If index = returnString.Length - 1 OrElse returnString.Chars(index + 1) <> space Then
returnString = returnString.Insert(index + 1, space)
End If
'get the next index
index = returnString.IndexOf(colon, index + 1)
End While
Return returnString
End Function
End Module

Answer 3

Public Module Module1
Public Sub Main()
dim nospace as string = EnsureSpace("xxx:")
dim space as string = EnsureSpace("xxx: ")
Console.WriteLine("|" + nospace + "|")
Console.WriteLine("|" + space + "|")
End Sub
private function EnsureSpace(val as string)
dim temp as string = val.trim
return temp.padright(temp.length + 1)
end function
' OR
private function EnsureSpace1(val as string)
return val.substring(0, val.LastIndexOf(":") + 1) + " "
end function
End Module
|xxx: |
|xxx: |

Answer 4

Three different approaches (all different from the other answers)...pick your poison:
(1) Using a helper Iterator function and String.Join():
Public Function AddSpaceAfterColons(ByVal input As String) As String
Return String.Join("", ColonHelper(input))
End Function
Public Iterator Function ColonHelper(ByVal input As String) As IEnumerable(Of Char)
Dim lastCh As Nullable(Of Char)
For Each ch As Char In input
If lastCh.HasValue AndAlso lastCh.Value = ":"c AndAlso Not (ch = " "c) Then
Yield " "c
End If
Yield ch
lastCh = ch
Next
If lastCh.HasValue AndAlso lastCh.Value = ":"c Then
Yield " "c
End If
End Function
(2) Walking backwards through a StringBuilder:
Public Function AddSpaceAfterColons(ByVal input As String) As String
Static colon As Char = ":"c
Static space As Char = " "c
Dim sb As New System.Text.StringBuilder(input)
For i As Integer = sb.Length - 1 To 0 Step -1
If sb(i) = colon Then
If i = (sb.Length - 1) OrElse sb(i + 1) = space Then
sb.Insert(i + 1, space)
End If
End If
Next
Return sb.ToString
End Function
(3) Using String.Split() and a StringBuilder:
Public Function AddSpaceAfterColons(ByVal input As String) As String
Dim sb As New System.Text.StringBuilder
Dim parts() As String = input.Split(":")
sb.Append(parts(0))
For i As Integer = 1 To parts.Length - 1
sb.Append(":")
If Not parts(i).StartsWith(" ") Then
sb.Append(" ")
End If
sb.Append(parts(i))
Next
Return sb.ToString
End Function