[RESOLVED] String manipulation _ Replace vs delete

[kayleigh]

For example http://www.vbforums.com/newthread.php?do=newthread&f=25

wanted to replace

http://www.vbforums.com to http://www.youtube.com

which would be better? Delete did not seem to work for me

[SickFinga]

Dim strURL As String = "http://www.vbforums.com/newthread.php?do=newthread&f=25"
strURL = strURL.Replace("http://www.vbforums.com", "http://www.youtube.com")

[kayleigh]

How odd. Well i dont understand why i used that before
for example

   Private _s As String = "http://www.vbforums.com/newthread.php?do=newthread&f=25"

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

 _s.Replace("http://www.vbforums.com", "http://www.youtube.com")

        MsgBox(_s)
    End Sub

returns same string? If i make dim as as string = _s

it works

[techgnome]

Replace is a FUNCTION ... ir RETURNS the string with the replacements in it. Look at what Sick posted:

strURL = strURL.Replace("http://www.vbforums.com", "http://www.youtube.com")

Now compare that with your attempt:

_s.Replace("http://www.vbforums.com", "http://www.youtube.com")

In fact, if you read the documentation for string.replace, you would see that in the description it says:

Returns a new string in which all occurrences of a specified string in the current instance are replaced with another specified string.

-tg

[kayleigh]

Yeh i just noticed that. thanks for the break down

[dbasnett]

If you are doing a lot of string replacements consider using stringbuilder

    Dim _sb As New System.Text.StringBuilder

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        _sb.Append("http://www.vbforums.com/newthread.php?do=newthread&f=25")

        _sb.Replace("http://www.vbforums.com", "http://www.youtube.com")

        Debug.WriteLine(_sb.ToString)

        _sb.Length = 0 'clear the string builder
    End Sub

[kayleigh]

Could string builder detect and strip everything after a certain char?

example

http://www.youtube.com/watch?v=_qQpLi6tuSM

http://www.youtube.com/watch

or

<urlhere>/audio/27XQR7Tk19XD?stream_token=aMXm0

<urlhere>/audio/27XQR7Tk19XD

[dbasnett]

Not directly. You could do this but it creates strings which is what we were try to avoid.

    Dim sb As New System.Text.StringBuilder

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        sb.Append("http://www.vbforums.com/newthread.php?do=newthread&f=25")

        sb.Replace("http://www.vbforums.com", "http://www.youtube.com")

        Debug.WriteLine(sb.ToString)

        Dim idx As Integer = sb.ToString.IndexOf("?")
        If idx <> -1 Then
            sb.Remove(idx, sb.Length - idx)
        End If

        Debug.WriteLine(sb.ToString)

        sb.Length = 0 'clear the string builder
    End Sub