Multiple Regex Replacements in C#

Question

I am trying create a Regex-based replacement for an article to automatically convert embedded references (many of them) in posts into the appropriate link and title format.

For example, given this:

I have already blogged about this topic ((MY TOPIC ID: "2324" "a number of times")) before.   And I have also covered ((MY TOPIC ID: "777" "similar topics")) in the past.

... I want to get this:

I have already blogged about this topic <a href='/post/2324'>a number of times</a> before.   And I have also covered <a href='/post/777'>similar topics</a> in the past.

I currently have this:

/* Does not work */
public static string ReplaceArticleTextWithProductLinks(string input)
{
    string pattern = "\\(\\(MY TOPIC ID: \\\".*?\\\" \\\".*?\\\"\\)\\)";
    string replacement = "<a href='/post/$1'>$2</a>";

    return Regex.Replace(input, pattern, replacement);
}

But it seems to return lines that contain <a href='/post/'></a> without appending matches instead of $1 and $2.

Question: What is the easiest way to do convert the string #1 above to string #2 above?

cdhowie · Accepted Answer · 2010-11-10 03:05:15Z

1

You're not capturing the parts of the expression you want to extract. Try something like this:

public static string ReplaceArticleTextWithProductLinks(string input)
{
    string pattern = @"\(\(MY TOPIC ID: ""(.*?)"" ""(.*?)""\)\)";
    string replacement = "<a href='/post/$1'>$2</a>";

    return Regex.Replace(input, pattern, replacement);
}

edited Nov 10, 2010 at 3:05

answered Nov 10, 2010 at 2:55

cdhowie

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2 Comments

jordanbtucker Over a year ago

C# does support the $1/$2 mechanism, but you're right about not capturing any groups. If you update your answer, I'll vote you up.

cdhowie Over a year ago

Ah yes, you are right. Not sure why I never realized that. Updated.

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