Question

Basically, I am trying to find the following pattern in a multiline textbox:

[p]anyword bla bla anyword[/p]

1.) The pattern can occur n-times in the textbox and I also want it n-times to be found.

2.) Between [p] and [/p] can be any character including whitespaces and linebreaks (“\r\n” in C#)

3.) I want the whole pattern, inluding the [p] and [/p]

The following code is very near to my wanted result. The problem is, that multiple linebreaks can occur between [p] and [/p]. I have tried out many many solutions. Nothing worked for me.

private void getTextFromTag2(String Tag, String txt)
{
    txt = txt.Replace("\r", "");

    string re1 = "(\\[";    
    string re2 = "p";   
    string re3 = "\\]"; 
    string re4 = ".*";  // Here lies the problem
    string re5 = "";    // Left open for a solution => \r\n cann occur n-times
    string re6 = "\\["; 
    string re7 = "\\/"; 
    string re8 = "p";   
    string re9 = "\\])";    

    Regex r = new Regex(re1 + re2 + re3 + re4 + re5 + re6 + re7 + re8 + re9, RegexOptions.IgnoreCase | RegexOptions.Multiline);

    MatchCollection mc = r.Matches(txt, 0);

    foreach (Match match in mc)
    {
        String c1 = match.Groups[1].ToString();
        Console.Write(c1 + "\r\n");
    }

}

As you might see, I already replaced “\r” with “” in txt, because the RegEx engine of .NET seems to want only “\n” as a new line character.

I think, the problem in my code is to be found in re4 and re5. re4 finds any character and works good, as long as there are no line breaks.

I think, re4 should say “any character, including whitespaces and \n”. But I really don’t get it.

So once again: Everting works fine, even if the pattern occurs many times in the textbox. The problem is, when linebreaks occur between [p] and [/p]

Here is an examle that does NOT work

[p]BlaBla BlaBla \r\n
BlaBla BlaBla \r\n
\r\n
BlaBla
[/p]

Here is an examle that DOES work

[p]BlaBla BlaBla[/p]
\r\n
\r\n
[p]Even more BlaBla[/p]
\r\n
\r\n
[p]Much more BlaBla[/p]

Please excuse my english. I am not a native english speaker.

Thank you.

This is the code, that now works for me. The changed things are //Changed Tagged

private void getTextFromTag2(String Tag, String txt)
    {
        //txt = txt.Replace("\r", ""); //Changed

        string re1 = "(\\[";     
        string re2 = "p";    
        string re3 = "\\]";  
        string re4 = ".*";   
        string re5 = "?";   // Changed
        string re6 = "\\["; 
        string re7 = "\\/"; 
        string re8 = "p";   
        string re9 = "\\])";    

        Regex r = new Regex(re1 + re2 + re3 + re4 + re5 + re6 + re7 + re8 + re9, RegexOptions.IgnoreCase | RegexOptions.Multiline | RegexOptions.Singleline); //Changed

        MatchCollection mc = r.Matches(txt, 0);

        foreach (Match match in mc)
        {
            String c1 = match.Groups[1].ToString();
            Console.Write(c1 + "\r\n");
        }

    }

Thank you so much.

Answer 1

You need to specify the Singleline option

Specifies single-line mode. Changes the meaning of the dot (.) so it matches every character (instead of every character except \n).

Basically the “Dot-matches-all” option you may be familiar with from other languages. The Multiline option you set only affects the behavior of the matching the beginning and ending of a line. See RegexOption class for more details.

Regex r = new Regex(regex, RegexOptions.IgnoreCase | RegexOptions.Singleline);

The other issue with the regex you provided is the * is greedy. so [p][/p][p][/p] would be a single match (it matched on the first [p] and the last [/p]. changing your re5 to:

string re5 = "?";    // Non-greedy match on *

Will fix that so you get two seperate matches.