Question

How to check if a string is a palindrome ignoring case and non-alphanumeric characters in VB.NET

Answer 1

Imports System
Imports System.Text
Imports System.Linq

Class PalindromeChecker
    Private Shared Function IsPalindrome(ByVal str As String) As Boolean
        Dim filtered As StringBuilder = New StringBuilder()

        For Each ch As Char In str
            If Char.IsLetterOrDigit(ch) Then
                filtered.Append(Char.ToLower(ch))
            End If
        Next

        Dim clean As String = filtered.ToString()
        Console.WriteLine(clean)
	
        Dim reversed As String = New String(clean.Reverse().ToArray())
        Return clean = reversed
    End Function

	Public Shared Sub Main()
        Dim input As String = "+^-Ab#c!D 50...#  05*()dcB[]A##@!$"

        If IsPalindrome(input) Then
            Console.WriteLine("The string is a palindrome.")
        Else
            Console.WriteLine("The string is not a palindrome.")
        End If
    End Sub
End Class



' run:
'   
' abcd5005dcba
' The string is a palindrome.
'

 

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Answer 2

Imports System
Imports System.Linq
Imports System.Text.RegularExpressions

Class PalindromeChecker
    Public Shared Function IsPalindrome(ByVal s As String) As Boolean
        Dim normalized As String = Regex.Replace(s, "[^a-zA-Z0-9]", "").ToLower()
        Console.WriteLine(normalized)
		
        Dim reversed As String = New String(normalized.Reverse().ToArray())
        
		Return normalized = reversed
    End Function

    Public Shared Sub Main()
        Dim s As String = "+^-Ab#c!D 50...#  05*()dcB[]A##@!$"
		
        Console.WriteLine(IsPalindrome(s))
    End Sub
End Class



' run:
'   
' abcd5005dcba
' True
'

 

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