I have a string containing HTML and I need to replace some words to be links - I do this with the following code;
string lNewHTML = Regex.Replace(lOldHTML, "(\bword1\b|\bword2|word3\b)", "$1", RegexOptions.IgnoreCase);
The code works, but I need to include some exceptions to the replace - e.g. I will not replace anything i an img-, li- and a-tag (including link-text and attributes like href and title) but still allow replacements in p-, td- and div-tags.
Can anyone figure this one out?
Ok, after some time of trying to construct a fitting regex, here my try.. This might need additional work, but should point you in the right direction.
I am matching the words "word1" and "word2", not inside a "tag1" or "tag2" tag. You need to adjust this to your needs, of course. Enable RegexOptions.IgnorePatternWhitespace, if you'd like to keep my formatting.
Unfortunatly, I have come up with a regex you could simply plug into Regex.Replace, since this Regex will match the whole String since the match before, but the word you are concerned with is in the first group. This group contains index and length of the word, so you can easily replace it using String.Substring...
(?:
\G
(?:
(?>
<tag1(?<N>)
|<tag2(?<N>)
|</tag1(?<-N>)
|</tag2(?<-N>)
|.)*?
(?(N)(?!))
)*
)
(word1|word2)
You need to use the Replace overload with the MatchEvaluator parameter so that you examine each match and decide whether to replace or not.
Related
So i have the following RegEx for the purpose of finding and adding whitespace:
(\S)(\()
So for a string like "SomeText(Somemoretext)" I want to update this to "SomeText (Somemoretext)" it matches "t(" and so my replace eliminates the "t" from the string which is not good. I also do not know what the character could be, I'm merely trying to find the non-existence of whitespace.
Is there a better expression to use or is there a way to exclude the found character from the match returned so that I can safely replace without catching characters i do not want to replace?
Thanks
I find lookarounds hard to read and would prefer using substitutions in the replacement string instead:
var s = Regex.Replace("test1() test2()", #"(\S)\(", "$1 (");
Debug.Assert(s == "test1 () test2 ()");
$1 inserts the first capture group from the regex into the replacement string which is the non-space character before the opening parenthesis (.
If you need to detect the absence of space before a specific character (such as bracket) after a word, how about the following?
\b(?=[^\s])\(
This will detect words ( [a-zA-z0-9_] that are followed by a bracket, without a space).
(if I got your problem correctly) you can replace the full match with ( and get exactly what you need.
In case you need to look for absence spaces before a symbol (like a bracket) in any kind of text (as in the text may be non-word, such as punctuation) you might want to use the following instead.
^(?:\S*)(\()(?:\S*)$
When using this, your result will be in group 1, instead of just full match (which now contains the whole line, if a line is matched).
I need help with my regex expression. I am trying to match keyword this but only when it is in parenthesis (this). So far I have:
(\()\bthis\b(\))
But looks like it also matches the parenthesis wrapping the word, while I only need to grab the word itself. Another issue is that it won't work if there are whitespaces inside the parenthesis: ( this )
What about group matching with that kind of REGEXP expression:
\((this)\)
Also if you want to match when there are white spaces (spaces, tabs, etc.):
\(\s*(this)\s*\)
Try it out here : Regex101. All the details about each character I'm using in the regex are detailed on that site.
You can retrieve the this value matched in the group by code. Please, check out the documentation related to the language you're using for that.
I want to find the href from an achore tag. So I have used regex as
<a\s*[^>]*\s*href\s*\=\s*([^(\s*|\>)]*)\s*[^>]*>\s*Text\s*<\/a>
Options = Ignorecase + singleline
Example
Text
So Group[1]="/abc/xzy/pqr.com"
But If the content is like
<a href="/abc/xzy/ //Contains new line
pqr.com" class="m">Text</a>
so Group[1]="/abc/xzy/
So I want to know how to get "/abc/xzy/pqr.com" if the content contains new line(\r\n)
Your capture group is a bit weird: [^(\s*|\>)]* is a character class and it will match any character not (, ror a character class \s, nor an asterisk *, etc.
What you can do however is to put quotes before and after the capture group:
<a\s*[^>]*\s*href\s*\=\s*"([^(\s*|\>)]*)"\s*[^>]*>\s*Text\s*<\/a>
^ ^
And then change the character class to [^"] (not quotes):
<a\s*[^>]*\s*href\s*\=\s*"([^"]*)"\s*[^>]*>\s*Text\s*<\/a>
^^^^
regex101 demo.
This said, it would be better to use a proper html parser instead of regex. It's just that it's more tedious to make a suitable regex because you can forget about a lot of different scenarios, but if you're certain of how your data comes through, regex might be a quick way to get what you need.
If you want to consider single quotes and no quotes at all in some cases, you might try this instead:
<a\s*[^>]*\s*href\s*=\s*((?:[^ ]|[\n\r])+)\s*[^>]*>\s*Text\s*<\/a>
Updated regex101.
This regex has this part instead (?:[^ ]|[\n\r])+ which accepts non-spaces and newlines (and carriage returns just in case). Note that \s contains white spaces, tabs, newlines and form-feed.
I'm currently facing a (little) blocking issue. I'd like to replace a substring by one another using regular expression. But here is the trick : I suck at regex.
Regex.Replace(contenu, "Request.ServerVariables("*"))",
"ServerVariables('test')");
Basically I'd like to replace whatever is between the " by "test". I tried ".{*}" as a pattern but it doesn't work.
Could you give me some tips, I'd appreciate it!
There are several issues you need to take care of.
You are using special characters in your regex (., parens, quotes) -- you need to escape these with a slash. And you need to escape the slashes with another slash as well because we 're in a C# string literal, unless you prefix the string with # in which case the escaping rules are different.
The expression to match "any number of whatever characters" is .*. In this case, you would want to match any number of non-quote characters, which is [^"]*.
In contrast to (1) above, the replacement string is not a regular expression so you don't want any slashes there.
You need to store the return value of the replace somewhere.
The end result is
var result = Regex.Replace(contenu,
#"Request\.ServerVariables\(""[^""]*""\)",
"Request.ServerVariables('test')");
Based purely on my knowledge of regex (and not how they are done in C#), the pattern you want is probably:
"[^"]*"
ie - match a " then match everything that's not a " then match another "
You may need to escape the double-quotes to make your regex-parser actually match on them... that's what I don't know about C#
Try to avoid where you can the '.*' in regex, you can usually find what you want to get by avoiding other characters, for example [^"]+ not quoted, or ([^)]+) not in parenthesis. So you may just want "([^"]+)" which should give you the whole thing in [0], then in [1] you'll find 'test'.
You could also just replace '"' with '' I think.
Taryn Easts regex includes the *. You should remove it, if it is just a placeholder for any value:
"[^"]"
BTW: You can test this regex with this cool editor: http://rubular.com/r/1MMtJNF3kM
I am updating some code that I didn't write and part of it is a regex as follows:
\[url(?:\s*)\]www\.(.*?)\[/url(?:\s*)\]
I understand that .*? does a non-greedy match of everything in the second register.
What does ?:\s* in the first and third registers do?
Update: As requested, language is C# on .NET 3.5
The syntax (?:) is a way of putting parentheses around a subexpression without separately extracting that part of the string.
The author wanted to match the (.*?) part in the middle, and didn't want the spaces at the beginning or the end from getting in the way. Now you can use \1 or $1 (or whatever the appropriate method is in your particular language) to refer to the domain name, instead of the first chunk of spaces at the beginning of the string
?: makes the parentheses non-grouping. In that regex, you'll only pull out one piece of information, $1, which contains the middle (.*?) expression.
What does ?:\s* in the first and third registers do?
It's matching zero or more whitespace characters, without capturing them.
The regex author intends to allow trailing whitespace in the square-bracket-tags, matching all DNS labels following the "www." like so:
[url]www.foo.com[/url] # foo.com
[url ]www.foo.com[/url ] # same
[url ]www.foo.com[/url] # same
[url]www.foo.com[/url ] # same
Note that the regex also matches:
[url]www.[/url] # empty string!
and fails to match
[url]stackoverflow.com[/url] # no match, bummer
You may find this Regular Expressions Cheat Sheet very helpful (hopefully). I spent ages trying to learn Regex with no luck. And once I read this cheat-sheet - I immediately understood what I previously failed to learn.
http://krijnhoetmer.nl/stuff/regex/cheat-sheet/