Compare two strings and get the differance

Hi,

I have 2 strings

string1 = "abcdefgh"
string2 = "abcdefghijklm"

I want to get the difference of the two strings .....

like getDiff(str2,str1) = "ijklm"

and where the diffrance is

like

getDiffStart(str2,str1) = 8 (where the last commom charcater is)

...........

Please help

use the mid$ function in a loop to grab one char at a time from each string and compare them

you mean something like this? :

VB Code:

[color=blue]Private Sub[/color] Command1_Click()
MsgBox GetDifference("abcdefgh", "abcdefghijklm")
[color=blue]End Sub[/color]
 
[color=blue]Private Function[/color] GetDifference([color=blue]ByVal[/color] stringA [color=blue]As String[/color], [color=blue]ByVal[/color] stringB [color=blue]As String[/color]) [color=blue]As String[/color]
GetDifference = [color=blue]Replace[/color](stringB, stringA, "")
[color=blue]End Function[/color]

VB Code:

Private Sub Form_Load()
Debug.Print GetDiff("Hello", "Hellohihow")
Debug.Print getDiffStart("Hello", "Hellohihow")
 
End Sub
Public Function GetDiff(S1 As String, S2 As String) As String
    If Len(S1) > Len(S2) Then
        GetDiff = Replace(S1, S2, "")
    Else
        GetDiff = Replace(S2, S1, "")
    End If
End Function
Public Function getDiffStart(S1 As String, S2 As String) As Integer
Dim Res As String
Res = GetDiff(S1, S2)
  If Len(Res) Then
       If Len(S1) > Len(S2) Then
           getDiffStart = InStr(1, S1, Res)
        Else
            getDiffStart = InStr(1, S2, Res)
       End If
  End If
End Function

What if the two strings are

s1 = "abcdefgh"

s2 = "abgh"

I need to get the difference which is "cde" and where it starts .....

I have richtext box called rtf1

and when the user presses my "Undo" or "Redo" button I want to highlite the difference .....

like in worpad when you delete something and press CTRL + Z the part you delected get's highlited ........


I currently use something like this .........

Code:

---


' The Redo Part .......... Very Messy Coding

'On Error Resume Next
ignore = True
LockWindowUpdate Me.hwnd
If Not undo(undocount + 1) = "" Then
    SelStart = rtfText.SelStart
    sellen = rtfText.SelLength
 
    undocount = undocount + 1
    RichText1.TextRTF = undo(undocount)
   
    If Len(RichText1.Text) > Len(rtfText.Text) Then
        If Left(RichText1.Text, Len(rtfText.Text)) = rtfText.Text Then
            SelStart = Len(rtfText.Text)
            sellen1 = Abs(Len(RichText1.Text) - Len(rtfText.Text))
        End If
    End If
   
    rtfText.TextRTF = undo(undocount) ' load the next text
    Timer5.Enabled = False
   
    If Not sellen1 > 0 Then
        rtfText.SelStart = SelStart + sellen
    Else
        rtfText.SelStart = SelStart ' + sellen
        rtfText.SelLength = sellen1
    End If
   
    RichText1.TextRTF = ""
    undolen = Len(rtfText.TextRTF)
    Call rtfText_SelChange
End If
LockWindowUpdate 0
ignore = False

---

Quote:

---

What if the two strings are

s1 = "abcdefgh"

s2 = "abgh"

I need to get the difference which is "cde" and where it starts .....

---

use the mid$ function in a loop to grab one char at a time from each string and compare them

Quote:

---

Originally posted by phinds
use the mid$ function in a loop to grab one char at a time from each string and compare them

---

Well ........ it does not work correctly in strings which contain vbcrlf ..... (I tried)

The Replace and Instr Combinations work on spesific string stypes i encountered .....

for eg. s1 = hello'hi'hello'hi'hello'hi'hello'hi'
s2 = hello'hi'hello''hello'hi'hello'hi'

U c.......... what i mean ......... when middle 'hi' is deleted and we use the

instr function to get the start of the difference .......
Or use replace here ......... it won't work

........... Please help if you guys nkow anything I could use to highlight the diffrence in RTFTEXT box when the user deletes some text and presses Ctrl + Z

Quote:

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Well ........ it does not work correctly in strings which contain vbcrlf ..... (I tried)

---

don't know what you tried, but the mid$ function doesn't care about vbCrLf and this technique WILL work on any pair of strings. If you have code that "doesn't work", post it.

Quote:

---

Originally posted by phinds
don't know what you tried, but the mid$ function doesn't care about vbCrLf and this technique WILL work on any pair of strings. If you have code that "doesn't work", post it.

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Code:

---


Function getdiffstart(str1 as string,str2 as string) as integer

for i = 0 to len(str2) - 1

if mid(str2,i,1) <> mid(str1,i,1) then
  getdiffstart = i
  exit for
end if

next i

End function

' the way to get the actual difference is more complex

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Can you uh... perhaps shorten your sig a bit? You got to admit, it is blooming huge!

Quote:

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Originally posted by LITHIA
"Can you uh... perhaps shorten your sig a bit? You got to admit, it is blooming huge!"

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Said the desert to the grain of sand ................ lol :D :)