Regex matching first occurrence only? - html

Question

This is the problem:
Code:
Dim findtext As String = "(?<=<hello>)(.*?)(?=</hello>)"
Dim myregex As String = TextBox1.Text
Dim doregex As MatchCollection = Regex.Matches(myregex, findtext)
MsgBox(doregex(0).ToString)
TextBox1:
<hello>1</hello>
<hello>2</hello>
<hello>3</hello>
So, when i run the code, it shows MsgBox with 1. Why only 1? Why not 2 and 3?
I added ? to .*, but it's still the same.

Answer 1

The MatchCollection contains multiple items but you are only retrieving the first one with doregex(0). Use a loop to get to the others:
Dim doregex As MatchCollection = Regex.Matches(myregex, findtext)
For Each match As Match In doregex
MsgBox(match.ToString)
Next
EDIT:
To combine the values, append them to a String within the loop before you use it:
Dim doregex As MatchCollection = Regex.Matches(myregex, findtext)
Dim matches As String = "" ' consider StringBuilder if there are many matches
For Each match As Match In doregex
matches = matches + match.ToString + " "
Next
MsgBox(matches)

Answer 2

Because you show only the first item in MatchCollection , you can use For Each loop to show all items like this :
For Each item In doregex
MsgBox(item.ToString)
Next
You can combine items with many way, belows one of them :
Dim result As String = String.Empty
For Each item In doregex
result = String.Format("{0} {1}", result, item)
Next
MsgBox(result)

Answer 3

Use LINQ:
Dim text_box_text = "<hello>1</hello>" & vbLf & "<hello>2</hello>" & vbLf & "<hello>3</hello>"
Dim findtext As String = "(?<=<hello>)(.*?)(?=</hello>)"
Dim my_matches_1 As List(Of String) = System.Text.RegularExpressions.Regex.Matches(text_box_text, findtext) _
.Cast(Of Match)() _
.Select(Function(m) m.Value) _
.ToList()
MsgBox(String.Join(vbLf, my_matches_1))
Also, with this code, you do not need to use the resource-consuming lookarounds. Change the regex to
Dim findtext As String = "<hello>(.*?)</hello>"
and use .Select(Function(m) m.Groups(1).Value) instead of .Select(Function(m) m.Value).