Question

I’m trying to make a function in VB.net that will loop through an algorithm. I’ve split the algorithm into an array using the Split command, so I have an array with the values.
I then try to loop through them and replace a # with “Number” where necessary, however VB.net throws an error.
I’m fairly new to VB.net, so I’m unsure why it’s doing this.
Algorithms are in the format A B C D E F 1 2 3 #

Function generate(ByVal alg As String)
    Dim algSplit As String() = alg.Split(" ")
    For Each digit In algSplit
        Dim replacement As String = algSplit(digit).Replace("#", "Number")
        algSplit(digit) = replacement
    Next
    Dim result As String = String.Join("", algSplit)
    MsgBox(result)
End Function

Is there a quick fix?

Question Part 2: I got the loop working; however I broke part of the functionality I was aiming for.

Public Function GetRandom(ByVal Min As Integer, ByVal Max As Integer) As Integer
    Dim Generator As System.Random = New System.Random()
    Return Generator.Next(Min, Max)
End Function
Public Function RandLet() As String
    Dim number As Integer = GetRandom(1, 26)
    Dim Alphabet() As String = New String() {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V""W", "X", "Y", "Z"}
    Dim Letter As String = Alphabet(number)
    Return Letter
End Function
Function generate(ByVal alg As String) As String
    Dim algSplit As String() = alg.Split(" "c)

    For index As Int32 = 0 To algSplit.Length - 1
        algSplit(index) = algSplit(index).Replace("#"c, GetRandom(1, 9)).Replace("%"c, RandLet())
    Next
    Dim result As String = String.Join("", algSplit)
    MsgBox(result)
    Return result
End Function

End result from A B C D E F 1 2 3 | L % % % | N # # # ends up as ABCDEF123|LXXX|N888
Essentially, each # and each % are being replaced by the same number instead of a different one each time. I thought that being in a loop this wouldn’t happen, what have I missed?

Answer 1

That’s probably easier with LINQ:

Dim value = "A B C D E F 1 2 3 #"
Dim replaced = From digit In value.Split(" "c)
             Select digit.Replace("#"c, "Number")
Dim result = String.Join("", replaced)

Your “traditional” approach, corrected:

Function generate(ByVal alg As String) As String
    Dim algSplit As String() = alg.Split(" "c)

    For index As Int32 = 0 To algSplit.Length - 1
        algSplit(index) = algSplit(index).Replace("#"c, "Number")
    Next
    Dim result As String = String.Join("", algSplit)
    Return result
End Function

1. Methods(Functions in VB) must return something. Your function doesn’t return anything, hence add AS String at the end.
2. Split has several overloads, the one you’re using takes a Char instead of string, so replace alg.Split(" ") with alg.Split(" "c)
3. If you want to replace an array value with something other, it’s better to you a For-Loop instead of a For-Each since you need to use the index often (see above)