RosettaCodeData/Task/Reverse-a-string/Visual-Basic-.NET/reverse-a-string.vb

58 lines
1.9 KiB
VB.net

#Const REDIRECTOUT = True
Module Program
Const OUTPATH = "out.txt"
ReadOnly TestCases As String() = {"asdf", "as⃝df̅", "Les Misérables"}
' SIMPLE VERSION
Function Reverse(s As String) As String
Dim t = s.ToCharArray()
Array.Reverse(t)
Return New String(t)
End Function
' EXTRA CREDIT VERSION
Function ReverseElements(s As String) As String
' In .NET, a text element is series of code units that is displayed as one character, and so reversing the text
' elements of the string correctly handles combining character sequences and surrogate pairs.
Dim elements = Globalization.StringInfo.GetTextElementEnumerator(s)
Return String.Concat(AsEnumerable(elements).OfType(Of String).Reverse())
End Function
' Wraps an IEnumerator, allowing it to be used as an IEnumerable.
Iterator Function AsEnumerable(enumerator As IEnumerator) As IEnumerable
Do While enumerator.MoveNext()
Yield enumerator.Current
Loop
End Function
Sub Main()
Const INDENT = " "
#If REDIRECTOUT Then
Const OUTPATH = "out.txt"
Using s = IO.File.Open(OUTPATH, IO.FileMode.Create),
sw As New IO.StreamWriter(s)
Console.SetOut(sw)
#Else
Try
Console.OutputEncoding = Text.Encoding.ASCII
Console.OutputEncoding = Text.Encoding.UTF8
Console.OutputEncoding = Text.Encoding.Unicode
Catch ex As Exception
Console.WriteLine("Failed to set console encoding to Unicode." & vbLf)
End Try
#End If
For Each c In TestCases
Console.WriteLine(c)
Console.WriteLine(INDENT & "SIMPLE: " & Reverse(c))
Console.WriteLine(INDENT & "ELEMENTS: " & ReverseElements(c))
Console.WriteLine()
Next
#If REDIRECTOUT Then
End Using
#End If
End Sub
End Module