Replace multiple characters in string in one line of code in VB.NET

If I read this correctly, you're trying to strip a list of characters from a string. This is a good fit for a RegEx.

Console.WriteLine(Regex.Replace("abcdefghijklmnop", "[acegi]", string.Empty))

(you'll need to import System.Text.RegularExpressions)

The RegEx approach is the best suited, but what I really need to say is:

Please, for the love of maintenance developers, don't get hung-up on getting this down to 1 line of code. One method call is your real goal, if you end up just piling a bunch of calls into 1 line to say it's one-line then you're shooting yourself in the foot.

I didn't believe Bittercode as he said that LINQ would outperform regex. So I did a little test just to be sure.

Three examples of how to do this:

Dim _invalidChars As Char() = New Char() {"j"c, "a"c, "n"c}
Dim _textToStrip As String = "The quick brown fox jumps over the lazy dog"

Private Sub btnStripInvalidCharsLINQ_Click(sender As System.Object, e As System.EventArgs) Handles btnStripInvalidCharsLINQ.Click
    Dim stripped As String = String.Empty
    Dim sw As Stopwatch = Stopwatch.StartNew
    For i As Integer = 0 To 10000
        stripped = _textToStrip.Where(Function(c As Char) Not _invalidChars.Contains(c)).ToArray
    Next
   sw.Stop()

    lblStripInvalidCharsLINQ.Text = _stripped & " - in " & sw.Elapsed.TotalMilliseconds & " ms"
End Sub

Private Sub btnStripInvalidCharsFOR_Click(sender As System.Object, e As System.EventArgs) Handles btnStripInvalidCharsFOR.Click
    Dim stripped As String = String.Empty
    Dim sw As Stopwatch = Stopwatch.StartNew
    stripped = _textToStrip
    For i As Integer = 0 To 10000
        For Each c As Char In _invalidChars
            stripped = stripped.Replace(c, "")
        Next
    Next
    sw.Stop()

    lblStipInvalidcharsFor.Text = stripped & " - in " & sw.Elapsed.TotalMilliseconds & " ms"
End Sub

Private Sub btnStripInvalidCharsREGEX_Click(sender As System.Object, e As System.EventArgs) Handles btnStripInvalidCharsREGEX.Click
    Dim stripped As String = String.Empty
    Dim sw As Stopwatch = Stopwatch.StartNew
    For i As Integer = 0 To 10000
        stripped = Regex.Replace(_textToStrip, "[" & New String(_invalidChars) & "]", String.Empty)
    Next
    sw.Stop()

    lblStripInvalidCharsRegex.Text = stripped & " - in " & sw.Elapsed.TotalMilliseconds & " ms"
End Sub

The results:

So, the for loop with string.replace outperformes all the other methods.

Because of this I would make an extension function to the string object.

Module StringExtensions
<Extension()> _
Public Function ReplaceAll(ByVal InputValue As String, ByVal chars As Char(), replaceWith As Char) As String
    Dim ret As String = InputValue
    For Each c As Char In chars
        ret = ret.Replace(c, replaceWith)
    Next
    Return ret
End Function

Then you could use this function nice and readably in one line:

_textToStrip.ReplaceAll(_invalidChars, CChar(String.Empty))

EDIT (10 years later):

I once again needed this to be as fast as possible.
I wrote a real performance test this time (benchmarkdotnet).
I used net6.0.

Code available in github: https://github.com/j-dc/stackoverflow_1332454

    //[SimpleJob(RuntimeMoniker.Net462, baseline: true)]
    //[SimpleJob(RuntimeMoniker.Net48)]
    [SimpleJob(RuntimeMoniker.Net60)]
    [RPlotExporter]
    public class RemoveChars {
        private static readonly char[] _invalidChars = new[] { 'j', 'a', 'n' };
        private static readonly string _textToStrip = "The quick brown fox jumps over the lazy dog";

        private static readonly HashSet<char> _invalidHash = new(new[] { 'j', 'a', 'n' });


        [Benchmark]
        public string Linq() {
            return new string(_textToStrip.Where(x => !_invalidChars.Contains(x)).ToArray());
        }

        [Benchmark]
        public string ForEach() {
            string ret = _textToStrip;
            foreach(char c in _invalidChars) {
                ret = ret.Replace(Convert.ToString(c), "");
            }
            return ret;
        }

        [Benchmark]
        public string Regexer() {
            return Regex.Replace(_textToStrip, $"[{new string(_invalidChars) }]", string.Empty);
        }

        [Benchmark]
        public string Hasher() {
            return new string(_textToStrip.Where(x => _invalidHash.Contains(x)).ToArray());
        }

        [Benchmark]

        public string Splitting() {
            return string.Join(string.Empty, _textToStrip.Split(_invalidChars, StringSplitOptions.RemoveEmptyEntries));
        }

        [Benchmark]
        public string Aggregate() {
            return _invalidChars.Aggregate(_textToStrip, (c1, c2) => c1.Replace(Convert.ToString(c2), ""));
        }


    }


}

Results:

I recommend Jon Galloway's approach, a regular expression is the appropriate method, and future developers will thank you for it :) - though it's not a difficult problem to solve with Linq as well. Here's some (untested) C# code to do that:

string stringToBeReplaced = "abcdefghijklmnop";
string charsToReplace = "acegi";
stringToBeReplaced = new String(stringToBeReplaced.Where(c => !charsToReplace.Any(rc => c == rc)).ToArray());

I suspect this code will probably perform slightly better then the regex equivalent, if performance is an issue.

The String class has a replace method to do this. You can use it this way:

YourString = YourString.Replace("OldValue", "NewValue")

What is the best way to repeat the line statement if you really want to use that code:

Sub Main() 

    Dim myString As String = Nothing
    Dim finalString As String = Nothing
    Console.Write("Please enter a string: ") 'your free to put anything
    myString = Console.ReadLine()
    finalString = myString.Replace("0", "")
    myString = finalString
    finalString = myString.Replace("1", "")
    myString = finalString
    finalString = myString.Replace("2", "")
    myString = finalString
    finalString = myString.Replace("3", "")
    myString = finalString
    finalString = myString.Replace("4", "")
    myString = finalString
    finalString = myString.Replace("5", "")
    myString = finalString
    finalString = myString.Replace("6", "")
    myString = finalString
    finalString = myString.Replace("7", "")
    myString = finalString
    finalString = myString.Replace("8", "")
    myString = finalString
    finalString = myString.Replace("9", "")
    Console.WriteLine(finalString)
    Console.ReadLine()
End Sub

For example: if you typed: 012ALP456HA90BET678 the output would be: ALPHABET.

Public Function SuperReplace(ByRef field As String, ByVal ReplaceString As String) As String
  ' Size this as big as you need... it is zero-based by default'
  Dim ReplaceArray(4) As String

  'Fill each element with the character you need to replace'

  ReplaceArray(0) = "WARD NUMBER "
  ReplaceArray(1) = "WN "
  ReplaceArray(2) = "WARD NO "
  ReplaceArray(3) = "WARD-"
  ReplaceArray(4) = "WARD "

  Dim i As Integer
  For i = LBound(ReplaceArray) To UBound(ReplaceArray)
    field = Replace(field, ReplaceArray(i), ReplaceString)
    Next i
  SuperReplace = field
End Function

Private Sub cmdTest_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdTest.Click
    Dim s As String = "México Juárez índice recúrso dirección"
    Dim arr() As String = {"á", "é", "í", "ó", "ú", "Ñ", "ñ"}
    Dim rep() As String = {"a", "e", "i", "o", "u", "N", "n"}
    Dim i As Integer = Nothing

    For i = 0 To UBound(arr)
        s = Replace(s, arr(i), rep(i))
    Next

    MsgBox(s)

End Sub