[2005] Removing repeated chars in a string

[Lasering]

Hi!!!

I have a string like this "23723567345", how can I do so I turn it into this "234567". The string can change can be like "345234". But the numbers it contains only go from 1 to 9.
In other words, how to remove the repeated chars in a string with only numbers from 1 to 9.

[Pino]

Hey Lasering,

When you say remove repeated chars, which way would you attack it from left to right or right to left?

Ie does...

12464849 = 124689 or 126849

Thanks

[Pino]

Anyway here is one way of doing it, Hastable might be a little overkill but will show you how it could be done.

        Dim myNumberStr As String = "568559722138735646"
        Dim usedNumbers As New Hashtable
        Dim endStr As String = ""

        For i As Integer = 1 To myNumberStr.Length - 1
            Dim curSel As String = myNumberStr.Substring(i, 1)
            If usedNumbers.Contains(curSel) = False Then
                'Add it
                usedNumbers.Add(curSel, curSel)
                endStr &= curSel
            End If
        Next

        MessageBox.Show(endStr)

Hope that helps!

[Lasering]

which way?? The way isn't important because if u remove the repeated chars from left to right or right to left u still would have the same number of numbers in the string. Yes the strings would be different but still with the same length and numbers just in a different order. I don't care about the order as long no repeated chars "stay" in the string.

[Pino]

Ok then my code above will work. I wasn't sure if the order was important.

Pino

[nbrege]

Here is a modified version of Pinos code (doesn't use a hashtable):

Dim myNumberStr As String = "568559722138735646"
Dim endStr As String = String.Empty

For Each curChar As Char In myNumberStr
    If Not endStr.Contains(curChar) Then
        endStr &= curChar
    End If
Next

MessageBox.Show(endStr)

The result is "568972134"

[user name]

Another way of approaching it only using the string you start with.

Dim myNumberStr As String = "568559722138735646"

        For i As Integer = myNumberStr.Length - 1 To 1 Step -1
            If myNumberStr.IndexOf(myNumberStr.Substring(i, 1)) < i Then
                myNumberStr = myNumberStr.Remove(i, 1)
            End If
        Next

        MessageBox.Show(myNumberStr)

[Pino]

Yes thats much better!

Good example.

Pino

[JuggaloBrotha]

For i As Integer = myNumberStr.Length - 1 To 1 Step -1

wouldn't you want:
For i As Integer = myNumberStr.Length - 1 To 0 Step -1

since you're starting from Length -1 and things like SubString are zero based?

I could be wrong on this one though

[penagate]

Just for fun, here's my angle. I think it's a bit more efficient than those posted so far.

Dim input As String = "568559722138735646"
Dim output As New StringBuilder(9)
Dim numbersFree As Bool() = _
  {True, True, True, True, True, True, True, True, True}
Dim sumOfUsed As Integer = 0

For Each c As Char In input
  Dim digit As Integer = CInt(c) - 49
  
  If (numbersFree(digit)) Then
    numbersFree(digit) = False
    sumOfUsed += digit + 1
    output.Append(c)
  Else If (sumOfUsed = 45) Then
    Exit For
  End If
Next

Console.WriteLine(output)

[user name]

JuggaloBrotha, The loop checks for anything repeating at an index before the character index so there is no need to check on the last one (first character).