VB Code for sentence cap

I'm trying to create a program that allows the user to type multiple sentences and after he clicks the button the program will capatilize the first letter of each sentence. I have done this but the sentences must have a double space after the period to work. I want the program to work even if the user only uses a single space after the period. Here is the code I have so far.

Dim strString As String
Dim searchStrTxt As Integer
Dim strCmpare As String
Dim strRplc As String
Dim strModified As String
Dim strFirstChr As String

strString = TextBox1.Text

strModified = strString
strFirstChr = UCase(Mid$(strModified, 1, 1))
strModified = strFirstChr & Mid$(strModified, 2)


'Search for single-spaced punctuation
For searchStrTxt = 1 To Len(strString) - 1
'DoEvents
strCmpare = Mid$(strModified, searchStrTxt, 3)
If strCmpare = ". " Then
strRplc = Mid$(strString, searchStrTxt, 4)
strModified = Replace$(strModified, strRplc, UCase$(strRplc))
End If

If strCmpare = "? " Then
strRplc = Mid$(strString, searchStrTxt, 4)
strModified = Replace$(strModified, strRplc, UCase$(strRplc))
End If

If strCmpare = "! " Then
strRplc = Mid$(strString, searchStrTxt, 4)
strModified = Replace$(strModified, strRplc, UCase$(strRplc))
End If
Next searchStrTxt

'Assign new string
TextBox1.Text = strModified

Thread moved from the FAQ forum (which is not the place to post your questions) to the 'VB.Net' forum (based on your previous post being VB2008).

I'd suggest looking for the periods rather the spacings or both together. As written languages are riddled with spaces. While the period only signifies the end of a sentence.

You can find the position of any ".", "!", "?" using IndexOf. Using that position work to your right in a loop skipping any spaces that fallow until you find your first letter. Which when you do, you can simply replace it with it's capitalized equivalent. Once complete, you now know to look for your next period and to repeat the process all over again.

you're using a lot of legacy code there. try this:

vb Code:

Private Function capitalizeSentences(ByVal s As String) As String
 
    Dim sentences() As String = s.Split(New String() {". ", "? ", "! ", Chr(10) & Chr(10), "." & Chr(10), "?" & Chr(10), "!" & Chr(10), Environment.NewLine & Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries)
    Dim newSentences() As String = DirectCast(sentences.Clone, String())
 
    Dim searchStart As Integer = 0
    For x As Integer = 0 To sentences.GetUpperBound(0)
 
        sentences(x) = sentences(x).Trim
        newSentences(x) = newSentences(x).Trim
        newSentences(x) = newSentences(x).Substring(0, 1).ToUpper & newSentences(x).Substring(1)
 
        Dim start As Integer = s.IndexOf(sentences(x), searchStart)
        For c As Integer = start To start + sentences(x).Length - 1
            s = s.Remove(c, 1)
            s = s.Insert(c, newSentences(x).Substring(c - start, 1))
        Next
        searchStart += sentences(x).Length + 2
 
    Next
 
    Return s
 
End Function