Imports System
Imports System.Text.RegularExpressions
Module Program
Sub Main()
Console.WriteLine("=== Testing: Get Word Before Last ===")
Console.WriteLine()
' Test cases to validate all edge conditions
Dim testCases() As String = {
"python vb.net",
" many spaces here now ",
"OneWord",
"",
" ",
"Hello, world!",
"Tabs" & Convert.ToChar(9) & "and" & Environment.NewLine & "newlines work too",
"Unicode 世界、こんにちは",
"Ends with punctuation.",
"Multiple words, with punctuation, here!",
"state-of-the-art program example"
}
For Each test In testCases
Dim result As String = GetWordBeforeLast(test)
Console.WriteLine($"Input: ""{test}""")
Console.WriteLine("Output: " & If(result, "null"))
Console.WriteLine(New String("-"c, 40))
Next
End Sub
''' <summary>
''' Returns the word before the last word in a string.
''' Handles Unicode, punctuation, multiple spaces, tabs, and edge cases.
''' </summary>
Function GetWordBeforeLast(text As String) As String
If String.IsNullOrWhiteSpace(text) Then
Return Nothing
End If
' Extract words (letters only)
' \p{L}+ handles Unicode letters
Dim matches = Regex.Matches(text, "\p{L}+")
' Need at least two words to return the one before the last
If matches.Count < 2 Then
Return Nothing
End If
' Return the second-to-last word
Return matches(matches.Count - 2).Value
End Function
End Module
' run:
'
' === Testing: Get Word Before Last ===
'
' Input: "python vb.net"
' Output: python
' ----------------------------------------
' Input: " many spaces here now "
' Output: here
' ----------------------------------------
' Input: "OneWord"
' Output: null
' ----------------------------------------
' Input: ""
' Output: null
' ----------------------------------------
' Input: " "
' Output: null
' ----------------------------------------
' Input: "Hello, world!"
' Output: Hello
' ----------------------------------------
' Input: "Tabs and
' newlines work too"
' Output: work
' ----------------------------------------
' Input: "Unicode 世界、こんにちは"
' Output: 世界
' ----------------------------------------
' Input: "Ends with punctuation."
' Output: with
' ----------------------------------------
' Input: "Multiple words, with punctuation, here!"
' Output: punctuation
' ----------------------------------------
' Input: "state-of-the-art program example"
' Output: program
'
