[RESOLVED] How to improve "search" performance?

[Dungeon Keeper]

Hello,

Im using For loop to cycle trough multiline texbox with lots of text, and Mid$ function to search for keywords within that text.

I have compared the search from Windows notepad and search from my application and my is several times slower when searching the same text?

Are there any ways to improve my search algorithm or a different algorithm.

I have a subquestion too. How can i copy the selected text from textbox using CTRL + C. Not the whole texbox, only text that is selected.

Regards!

[LaVolpe]

1. Not sure why you would need a For loop to search a textbox. InStr() can find selected text pretty quickly. You might want to post key parts of your search routine.

2. To copy selected text to the clipboard.
ClipBoard.Clear
Clipboard.SetText Text1.SelText

[Dungeon Keeper]

Thanks LaVolpe

Here is my search routine:

If KeyAscii = vbKeyReturn Then
        Dim a As String
        Dim br, b As Integer
        a = LCase$(Text2.Text)
        b = Len(Text2.Text)
        For br = Pocetak To Len(Text1.Text)
            If LCase$(Mid$(Text1.Text, br, b)) = a Then
                Text1.SetFocus
                Text1.SelStart = br - 1
                Text1.SelLength = b
                KeyAscii = 0
                If Pocetak < Len(Text1.Text) Then
                    Pocetak = br + 1
                Else
                    Pocetak = 1
                End If
                Exit Sub
            End If
        Next br
        KeyAscii = 0
        Pocetak = 1
    End If

Edit:

Program needs to remember where search ended so next time i hit enter it starts from that spot.
Pocetak is global variable.

[LaVolpe]

I think this would be much faster...

Dim lPos As Long
If Pocetak < 1 Then Pocetak = 1
lPos = InStr(Pocetak, Text1.Text, Text2.Text, vbTextCompare)
' change vbTextCompare to vbBinaryCompare for case-sensitivity
If lPos = 0 Then 
    ' text2 not found in text1
   ' may want to reset Pocetak here?
Else
    Text1.SelStart = lPos
    Text1.SelLength = Len(Text2.Text)
    Text1.SetFocus
    Pocetak = lPos + 1
End If

Does that work better?
Note Pocetak cannot be zero, it must start at a minimum of 1.

[Dungeon Keeper]

Yeah i know, my Pocetak is Globaly declared and is set to 1 on form load.

Ok, so this InStr function compres text1 to text2, its not case sensitive and it starts from Pocetak of text1? So if Pocetak is 51, InStr would search from 51st character?

[LaVolpe]

Yes to all except....
1. The case-sensitivity part. You dicatate that by changing the last parameter as I commented in the sample code.
2. It compares Text2 to Text1. It checks if Text2 is in Text1. If I got them reversed, then reverse them in the sample code.

Even though Pocetak is set to 1 on form load, there are other places you will want to reset it back to 1. For example, if no match is found? If user opts to search from beginning? If Text1 is replaced maybe? Maybe if the user clicks inside of Text1, then maybe Pocetak should be set to Text1.SelStart? Just think about it as if you were the user and wanted to search... when would you want to search from the beginning?

[Dungeon Keeper]

Yeah, you are right about those resets of Pocetnik. I'll implement some of your advices. Thanks a lot for the code, it works perfectly fast. I didnt know about this InStr function, well i heard about it, and ive seen it before but it didnt fell on my mind now when i needed it.

Resolved