Replace exact word - vb.net

Question

I want to convert this string:
"http://www.example.com/sms.aspx?user=joey&pass=joey123&mbno=9792234567&msg=Test"
to this:
"http://www.example.com/sms.aspx?user={0}&pass={1}&mbno={2}&msg={3}"
But I am getting output like this:
"http://www.example.com/sms.aspx?user={0}&pass={0}123&mbno={2}&msg={3}".
I have used the following line of code for replacing:
Dim SMSUrlStr As String="http://www.example.com/sms.aspxuser=joey&pass=joey123&mbno=9792234567&msg=Test"
e.g. Regex.Replace(SMSUrlStr, joey, {0})
but it is also replacing "joey" from "joey123".
How can I make the replacement more specific?

Answer 1

Instead of looking at the input as a string, you could regard it as a URI. There are methods in the framework to work with URIs, and from that we can rebuild it into the form you need:
Imports System.Collections.Specialized
Imports System.Text
Imports System.Web
Module Module1
Sub Main()
Dim s = "http://www.example.com/sms.aspx?user=joey&pass=joey123&mbno=9792234567&msg=Test"
Dim u = New Uri(s)
Dim q = HttpUtility.ParseQueryString(u.Query)
Dim newQ = q.AllKeys.Select(Function(p, i) p & "={" & i & "}")
Dim newS = u.GetLeftPart(UriPartial.Path) & "?" & String.Join("&", newQ)
Console.WriteLine(newS)
Console.ReadLine()
End Sub
End Module
Outputs:
http://www.example.com/sms.aspx?user={0}&pass={1}&mbno={2}&msg={3}