Include match index in Regex replacement string - asp.net

Question

I have a situation where I need to strip out HTML code from some text. However, some of the input text includes lists, and I want to retain the numbering in that case.
If I do
result = Regex.Replace(result, "<li>", vbNewLine & "1. ", RegexOptions.IgnoreCase)
Then after stripping out the other HTML tags, I end up with:
1. List item one
1. List item two
1. List item three
Is there a way to get the index of the match during replacement?
so for example:
result = Regex.Replace(result, "<li>", vbNewLine & replacementIndex + 1 & " ", RegexOptions.IgnoreCase)
Then after stripping out the other HTML tags, I would get:
1. List item one
2. List item two
3. List item three
Is this possible??
Note: This is inside a function, so that each list is handled separately, and unordered lists get bullets (*) instead.

Answer 1

This should be a good starting point. #"(\<ul\>)((.|\n)*?)(\<\/ul\>)" this will match everything in between the tags.

Answer 2

It's messy, but something like the following. Only change one at a time. This may be slow for large data sets.
int lineNbr = 1;
string newResult = result.Replace("(?i)<li>", vbNewLine & (lineNbr++).ToString() & '. ', 1);
while (newResult != result)
{
result = newResult;
newResult = result.Replace("(?i)<li>", vbNewLine & (lineNbr++).ToString() & '. ', 1);
}

Answer 3

Here's how I ended up doing it - first, find each ordered list:
Dim result As String = rawText
Dim orderedLists As MatchCollection = Regex.Matches(rawText, "<ol>.*?</ol>", RegexOptions.Singleline)
For Each ol As Match In orderedLists
result = Replace(result, ol.Value, EncodeOrderedList(ol.Value))
Next
And the function to convert each one:
Private Function EncodeOrderedList(ByVal rawText As String) As String
Dim result As String = rawText
result = Regex.Replace(result, "<ol>\s*<li>", "1. ", RegexOptions.IgnoreCase)
result = Regex.Replace(result, "</li>\s*</ol>", vbNewLine & vbNewLine, RegexOptions.IgnoreCase)
Dim bullets As MatchCollection = Regex.Matches(rawText, "</li>\s*<li>")
Dim i As Integer = 2
For Each li As Match In bullets
result = Replace(result, li.Value, vbNewLine & i & ". ", 1, 1)
i += 1
Next
Return result
End Function
I haven't tested it on nested lists.