C# , Regex replace all linebreak with
outside a bbcode code block

Question

I've been trying all day with no luck to regex replace the new line "\n" with a "<br />" but outside a code block like a "**[code]**some code...**[/code]**".

For example if I have the following

string myString = "Good luck **\n** thanks [code]my **\n** name[/code]";

How to replace the line breaks "\n" with "<br />" outside the code tag only, using regular expression?

If you're building a whole parser... don't do it with regular expressions. — Rawling, Mar 29 '12 at 15:39
@Rawling is right - look at writing a tokenizer/parser that works as a state machine. Take a look at the source code for the [HTML Agility Pack](http://htmlagilitypack.codeplex.com/) to see how it is done. — Oded, Mar 29 '12 at 15:41

score 2 · Answer 1 · edited May 23 '17 at 10:34

2

BBCode is not a regular language, so using regular expressions to parse it is not the best approach.

Look at writing a parser based on the character stream - take a look at the source code from the HTML Agility Pack to see how this is done (basically a state machine moving from character to character).

Alternatively, use one of the existing .NET BBCode parsers, as the answers to BBCode or wiki markup libraries for .NET? point to.

edited May 23 '17 at 10:34

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answered Mar 29 '12 at 15:45

Oded

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Thanks, can you give me a quick example in c# for example replacing the [b]this is bold[/b] to this is bold using the HTML Agility Pack ? – Mohamed Tarek Mar 29 '12 at 15:59
@MohamedTarek - No. The HTML Agility Pack is an _HTML_ parser. I pointed you to it as an example of how to write a parser. – Oded Mar 29 '12 at 16:00
Forgive my bad English I'm an ESL but I meant the regex pattern to replace all \n in a string with
except for the onse in [code] block. – Mohamed Tarek Mar 29 '12 at 16:05
@MohamedTarek - My answer is that regex is not appropriate (not good) for this. – Oded Mar 29 '12 at 16:10

score 0 · Accepted Answer · answered Mar 30 '12 at 09:47

Well, after trying and failing so many times I came up with the following code and it worked, it's vb.net BTW.

Public Function BBCode(ByVal strTextToReplace As String) As String
        Dim regExp As Regex
        strTextToReplace = strTextToReplace.Replace(Chr(10), "<br />")

        regExp = New Regex("\[code\]([^\]]+)\[\/code\]", RegexOptions.Singleline)
        Dim mc As MatchCollection = regExp.Matches(strTextToReplace)
        For Each m As Match In mc
            Dim gs = m.Groups()
            strTextToReplace = regExp.Replace(strTextToReplace, "<table cellpadding=""2"" cellspacing=""0"" class=""tbl_Quote""><tr><td dir=""rtl""><a class=""quote_Head"">code:</a></td></tr><tr><td><textarea class=""lined"" cols=""77"" readonly=""readonly"" rows=""1"" spellcheck=""false"">" & gs(1).Value.ToString.Replace("<br />", Chr(10)) & "</textarea></td></tr></table>", 1)
        Next
Return strTextToReplace
End Function

I hope this helps someone else.

This may very well fail if your BBCode is not well formed. That's why I suggested using an existing parser. — Oded, Apr 03 '12 at 18:25

C# , Regex replace all linebreak with outside a bbcode code block

2 Answers2

C# , Regex replace all linebreak with
outside a bbcode code block