How to parse string with block using regex?

Question

1.00/5 (3 votes)

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I have string input, and I want to use Regex to parse block data:

<L
  <H1 Category1>
  <L
    <L
      <H1 Food1>
      <L
        <H2 Banana>
        <H2 Orange>
      >
    >
    <L
      <H1 Wine1>
      <L
        <H2 Whisky>
        <H2 Vodka>
        <H2 Beer>
      >
    >
  >
>.

I then use Regex to parse, I want to get 2 match/group blocks like below:

<H1 Food1>
<L
   <H2 Banana>
   <H2 Orange>
>
	  	  
<H1 Wine1>
<L
   <H2 Whisky>
   <H2 Vodka>
   <H2 Beer>
>

What I have tried:

I tried get, but something did not match, demo link regex101: build, test, and debug regex[^]

My Regex:

(<H1\s+\w+>)(\s+<L\s+){1}(<H2.+?>\s*>)

Posted 17-Aug-23 16:43pm

headshot9x

Updated 14-Sep-23 6:14am

Deeksha Shenoy

v9

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Comments

Richard Deeming 18-Aug-23 3:50am

REPOST
How many times do you need to ask the same question?!
How to get total element tag in C#?[^]
How to parse string by element tag?[^]

headshot9x 20-Aug-23 7:51am

Hi, it's difference, don't conflict of them.

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OriginalGriff · Accepted Answer · 2023-08-17T18:45:00

Start by simplifying your regex and see what you get - remove the second and third classes:

RegEx

(<H1\s+\w+>)

If you run that, you will see that you get three groups:

Results

<H1 Category1>
<H1 Food1>
<H1 Wine1>

And that explains why your regex doesn't work: the first phrase captures the outer "Category1" phrase - so when you add the second and third, it assumes a single "L" phrase followed by an "H1" phrase, which it doesn't get.

Add regex to detect and ignore the outer phrase and you'll get there.