Regex Non-Greedy (Lazy)

Question

I'm attempting to non-greedily parse out TD tags. I'm starting with something like this:

<TD>stuff<TD align="right">More stuff<TD align="right>Other stuff<TD>things<TD>more things

I'm using the below as my regex:

Regex.Split(tempS, @"\<TD[.\s]*?\>");

The records return as below:

""
"stuff<TD align="right">More stuff<TD align="right>Other stuff"
"things"
"more things"

Why is it not splitting that first full result (the one starting with "stuff")? How can I adjust the regex to split on all instances of the TD tag with or without parameters?

Package

Please see #1732848 – Synonym

. just means a literal dot in character class [.], not 'any character. You may have more success with [^>]*, but it would break on a > in an attribute (which is one of the reasons why we often look at parsers rather the regexes to manipulate html & xml). – Gerhardine

@Gerhardine The HTML here is pretty static. There isn't much variation and I know the regex that would work for it. I didn't go the route of parsers because of that. Is there a way to make the . character mean 'any character' including whitespace? – Package

I don't know the c# modifiers (in pcre it would be /s) to make the dot match all. However [^>]*> is functionally equivalent to (.|\s)*?>, and probably easier on the regex. – Gerhardine

Answer 1

The regex you want is <TD[^>]*>:

<     # Match opening tag
TD    # Followed by TD
[^>]* # Followed by anything not a > (zero or more)
>     # Closing tag

Note: . matches anything (including whitespace) so [.\s]*? is redundant and wrong as [.] matches a literal . so use .*?.

Indignation

By default, . does not match new line but \s does. – Blase

Answer 2

For non greedy match, try this <TD.*?>

Gigantic

@Hambone Because ? after the quantifier * tells Regex engine to stop eating symbols when it finds the first match of the expression which follows ?, that is - >. The difference is because of greedy vs non-greedy *. – Electricity

Answer 3

From https://regex101.com/

• * Quantifier — Matches between zero and unlimited times, as many times as possible, giving back as needed (greedy)
• *? Quantifier — Matches between zero and unlimited times, as few times as possible, expanding as needed (lazy)

Tera