Question

My project has the need to build consistent urls similar to the ones here on stackoverflow. I know how I “can” do it by running the string through multiple filters, but I’m wondering if I can do it all with a single method.

Basically I want to remove all special characters, and replace them with dashes BUT if there are multiple dashes in a row, I need them to be a single dash. How can I implement this as clean as possible?

Example: If I were to use the following string.

My #1 Event

My regex would create the following string

my–1-event

notice how there are two dashes (one for the space and one for the “#” symbol). What I need is

my-1-event

Here’s how I’m implementing it currently

    ''# <System.Runtime.CompilerServices.Extension()>
    Public Function ToUrlFriendlyString(ByVal input As String) As String
        Dim reg As New Regex("[^A-Za-z0-9]")
        ''# I could run a loop filter here to match "--" and replace it with "-"
        ''# but that seems like more overhead than necessary.
        Return (reg.Replace(Trim(input), "-"))
    End Function

And then all I do is call the extension method

    Dim UrlFriendlyString = MyTile.ToUrlFriendlyString

Thanks in advance.

Answer 1

Add a + to the end of the regex.
This will tell it to match one or more characters that match the character class that precedes the +.

Also, you should create your Regex instance in a Shared field outside the method so that .Net won’t need to parse the regex again every time you call the method.

[edited by rockinthesixstring]: here’s the final result

    Private UrlRegex As Regex = New Regex("[^a-z0-9]+", RegexOptions.IgnoreCase)

    <System.Runtime.CompilerServices.Extension()>
    Public Function ToUrlFriendlyString(ByVal input As String) As String
        Return (UrlRegex.Replace(Trim(input), "-"))
    End Function