Replace two duplicate word into two different words

[yesrams]

Hi members, Can some one solve my code.

I need to Replace two duplicate word into two different words.

Like:

abc is a search engine and also abc a search engine.
to
google is a search engine and also yahoo a search engine.

I tried this.

TextBox1.Text = Replace(TextBox1.Text, "abc", "google")

But it replaces all abc to google. But I need to change first abc to google and second abc to yahoo and so on.

also tried this one

Dim m14 As MatchCollection = Regex.Matches(TextBox1.Text, "abc", RegexOptions.Singleline + RegexOptions.IgnoreCase)
For Each n1 As Match In m14
Dim value As String = n1.Groups(0).Value
'MsgBox(value)

If value.Contains("abc") Then

TextBox1.Text = Replace(TextBox1.Text, "abc", "google")

'MsgBox("found")

End If
Next

I Need some ones help.

[Sitten Spynne]

The regex solution is intuitive but gets ugly fast. You can look at the index of each match to see where it was, but once you make one replacement all future indices are invalid. But that's only true going forward. If you go backwards, you can rely on the indices. But then you have to deal with the case where there are more or less "abc" instances than words. Turns out that's not tough to deal with.

First I built some test cases. Let's say we want to replace in this order: "Google", "Yahoo", "DuckDuckGo". We need a string with 2, 3, and 4 "abc" instances to test out all of our cases. Here's my tests:

• "You got your abc in my abc."
• "I went to the dance and saw abc, abc, and abc."
• "I don't like abc, but it's not as bad as abc. Don't abc my abc."

Here's the algorithm I dreamed up:

* Find all matches for "abc" in the string.
* If there are more matches than replacements, remove the last matches.
* If there are more replacements than matches, ignore the last replacements.
* Starting at the last match and replacement:
	* Get the index of the match.
	* Remove "abc" from that index.
	* Insert the current replacement at the index.
	* Move to the previous match and previous replacement.

Here's the implementation:

' Import System.Text.RegularExpressions
Function ReplaceInSequence(ByVal input As String, ByVal target As String, ByVal replacements() As String) As String
	Dim pattern = String.Format("\b{0}\b", target)
	Dim patternMatches = Regex.Matches(input, pattern)

	' Life's easier later if we get the matches out of MatchCollection and into an array.
	Dim matches(patternMatches.Count - 1) As Match
	patternMatches.CopyTo(matches, 0)

	' If there are more targets than replacements, take only the first ones
	If matches.Count > replacements.Length Then
		matches = matches.Take(replacements.Length).ToArray()
	End If

	' If there are more replacements than matches, we ignore them by starting at the same
	' index in replacements as the last index of matches.
	Dim output As String = input
	For matchIndex = matches.Length - 1 To 0 Step -1
		Dim targetIndex As Integer = matches(matchIndex).Index

		' Remove the target from the string
		output = output.Remove(targetIndex, target.Length)

		' Insert the replacement
		output = output.Insert(targetIndex, replacements(matchIndex))
	Next

	Return output
End Function

Here's an example of how to use it (also how I tested):

Dim testStrings() = {"You got your abc in my abc.",
					 "I went to the dance and saw abc, abc, and abc.",
					 "I don't like abc, but it's not as bad as abc. Don't abc my abc."}
Dim replacements() = {"Google", "Yahoo", "DuckDuckGo"}

For Each value In testStrings
	Dim replaced = ReplaceInSequence(value, "abc", replacements)
	Console.WriteLine(replaced)
Next

There's a more memory-efficient way to do this with a StringBuilder, but it's a bit more complicated and I won't discuss it unless you come back with complaints you're getting OutOfMemoryException.