[2008] How to check if all the chars in a string are different from each other?

Hi!!

How can I check if all the chars in a string are different from each other? In other words how can I check if there are repeated chars in a string?

Thks a lot!

try this:

vb Code:

MsgBox("string contains duplicate characters = " & checkString("astringa"))

vb Code:

Private Function checkString(ByVal str As String) As Boolean
        
     For x As Integer = 0 To str.Length - 1
          If x > 0 Then
             If CStr(str.Substring(0, x) & str.Substring(x + 1, str.Length - (x + 1))).Contains(str.Substring(x, 1)) Then
                Return True
             End If
          Else
             If str.Substring(x + 1, str.Length - (x + 1)).Contains(str.Substring(x, 1)) Then
                 Return True
             End If
          End If
     Next
     Return False
 
End Function

Well, the question is a little bit vague. You don’t specify the casing. If the method should be case sensitive, than here is the method:

Code:

---

'Case sensitive
Private Function ContainsDuplicate(ByRef str As String) As Boolean
    For i As Integer = 0 To str.Length - 1
        If str.Substring(0, i).Contains(str.Substring(i, 1)) Then
            Return True
        End If
    Next
    Return False
End Function

---

If it is not spouse to be case sensitive, than add ToLower method after str and leave the rest the same, here is an example:

Code:

---

'None case sensitive
Private Function ContainsDuplicate(ByRef str As String) As Boolean
    For i As Integer = 0 To str.Length - 1
        If str.ToLower.Substring(0, i).Contains(str.ToLower.Substring(i, 1)) Then
            Return True
        End If
    Next
    Return False
End Function

---

vb.net Code:

For index As Integer = 0 To myString.Length - 1
    If myString.LastIndexOf(myString(index)) <> index Then
        'There is a least one more occurrence in the string of the character at the current index.
    End If
Next