Function convert cyrillic to latin

Question

I am trying to create custom convert cyrillic to latin text function in VB.net. I've never tried to make a custom function so I don't know what I am doing wrong. I have one problem and also, function doesn't work : Object reference not set to an instance of an object.

    Public Function ConvertCtoL(ByVal ctol As String) As String

    ctol = Replace(ctol, "Б", "B") 
    ctol = Replace(ctol, "б", "b")

**End Function** ' doesn't return a value on all code paths

Since I didn't found a solution for cyrillic to latin text I was planning to create function that would replace every letter from one alphabet to another.

Answer 1

You need Return ctol to tell it what value to return.

Perhaps researching "lookup table" would help you make a neater function.

Edit: The Wikipedia entry for Lookup table should be a good start.

Here is a simple example:

Imports System.Text

Module Module1

    Function ReverseAlphabet(s As String) As String
        Dim inputTable() As Char = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray()
        Dim outputTable() As Char = "ZYXWVUTSRQPONMLKJIHGFEDBCA".ToCharArray()
        Dim sb As New StringBuilder

        For Each c As Char In s
            Dim inputIndex = Array.IndexOf(inputTable, c)
            If inputIndex >= 0 Then
                ' we found it - look up the value to convert it to.
                Dim outputChar = outputTable(inputIndex)
                sb.Append(outputChar)
            Else
                ' we don't know what to do with it, so leave it as is.
                sb.Append(c)
            End If
        Next

        Return sb.ToString()

    End Function

    Sub Main()
        Console.WriteLine(ReverseAlphabet("ABC4")) ' outputs "ZYX4"
        Console.ReadLine()
    End Sub

End Module