Create a replace function in vb.net

Question

Please Help me in creating a replace function. Problem: Their is a alfanumeric value of any lenght (string) and i want to replace its all characters with 'X' except right four characters

Like : Value : 4111111111111111 Result Should be: XXXXXXXXXXXX1111

I have created a function but got stuck:

public function myfunction(str as string)
  str.Replace(str.Substring(0, str.Length - 5), 'X') 'but here i want no of x to be equvals to count of lenght of str - 4
end function

please tell me a better fuction to perform such a operation

Answer 1

Dim sNumber As String = "4111111111111111"
Dim sResult As String = StrDup(sNumber.Length - 4, "X"c) + Strings.Right(sNumber, 4)

Answer 2

Try this on for size.

Public Shared Function ObfuscateCardNumber(ByVal cardNumber As String) As String
    If cardNumber.Length <= 4 Then
        Return cardNumber
    Else
        Return cardNumber _
            .Substring(cardNumber.Length - 4, 4) _
            .PadLeft(cardNumber.Length, "X"c)
    End If
End Function

Answer 3

something like

string result for(int i = 0;i > str.length -4;i++) { result = result +x } result = result + str.substrin(get last 4)

Answer 4

I got my answer using sql server but i want it to be done in dotnet.

SELECT case when len(cardnum) > 4 then replicate('X',len(cardnum)-4) + RIGHT(cardnum,4) ELSE cardnum END from details