Develop Reference

How do I see if a string contains another string with quotes in it?

I am trying to see if a large string contains this line of HTML:
<label ng-class="choiceCaptionClass" class="ng-binding choice-caption">Was this information helpful?</label>
As you can see, this snippet has quotations in multiple places and it's causing problems when I do something like this:
Assert.IsTrue(responseContent.Contains("<label ng-class="choiceCaptionClass" class="ng - binding choice - caption">Was this information helpful?</label>"));
I've tried both of these ways of defining the string:
#"<label ng-class=""choiceCaptionClass"" class=""ng - binding choice - caption"">Was this information helpful?</label>"
and
"<label ng-class=\"choiceCaptionClass\" class=\"ng - binding choice - caption\">Was this information helpful?</label>"
But in each case the Contains() method looks for the literal string with either the double quotes or the backslashes. Is there another way I could define this string so I can correctly search for it?

Escaping the double-quotes with backslashes is the proper thing to do.
The reason your search may be failing is that the strings don't actually match. For example, in your version with backslashes, you have spaces around some of the dashes but your HTML string does not.

Try using regular expressions. I made this one for you but you can test your own regex here.
var regex = new Regex(#"<label\s+ng-class\s*=\s*""choiceCaptionClass""\s+class\s*=\s*""ng-binding choice-caption""\s*>\s*Was this information helpful\?\s*</label>", RegexOptions.IgnoreCase);
Assert.IsTrue(regex.IsMatch(responseContent));
If this is not working use the tester tool to figure it out what part of the pattern is getting off.
Hope this help!

Regex between, from the last to specific end

Today my wish is to take text form the string.
This string must be, between last slash and .partX.rar or .rar
First I tried to find edge's end of the word and then the beginning. After I get that two elements I merged them but I got empty results.
String:
http://hosting.xyz/1234/15-game.part4.rar.html
http://hosting.xyz/1234/16-game.rar.html
Regex:
Begin:(([^/]*)$) - start from last /
End:(.*(?=.part[0-9]+.rar|.rar)) stop before .partX.rar or .rar
As you see, if I merge that codes I won't get any result.
What is more, "end" select me only .partX instead of .partX.rar
All what I want is:
15-game.part4.rar and 16-game.rar
What i tried:
(([^/]*)$)(.*(?=.part[0-9]+.rar|.rar))
(([^/]*)$)
(.*(?=.part[0-9]+.rar|.rar))
I tried also
/[a-zA-Z0-9]+
but I do not know how select symbols.. This could be the easiest way. But this select only letters and numbers, not - or _.
If I could select symbols..

You don't really need a regex for this as you can merely split the url on / and then grab the part of the file name that you need. Since you didn't mention a language, here's an implementation in Perl:
use strict;
use warnings;
my $str1="http://hosting.xyz/1234/15-game.part4.rar.html";
my $str2="http://hosting.xyz/1234/16-game.rar.html";
my $file1=(split(/\//,$str1))[-1]; #last element of the resulting array from splitting on slash
my $file2=(split(/\//,$str2))[-1];
foreach($file1,$file2)
{
s/\.html$//; #for each file name, if it ends in ".html", get rid of that ending.
print "$_\n";
}
The output is:
15-game.part4.rar
16-game.rar

Nothing could be simpler! :-)
Use this:
new Regex("^.*\/(.*)\.html$")
You'll find your filename in the first captured group (don't have a c# compiler at hand, so can't give you working sample, but you have a working regex now! :-) )
See a demo here: http://rubular.com/r/UxFNtJenyF

I'm not a C# coder so can't write full code here but I think you'll need support of negative lookahead here like this:
new Regex("/(?!.*/)(.+?)\.html$");
Matched Group # 1 will have your string i.e. "16-game.rar" OR "15-game.part4.rar"

Use two regexes:
start to substitute .*/ with nothing;
then substitute \.html with nothing.
Job done!

How to extract string between 2 markers using Regex in .NET?

I have a source to a web page and I need to extract the body. So anything between </head><body> and </body></html>.
I've tried the following with no success:
var match = Regex.Match(output, #"(?<=\</head\>\<body\>)(.*?)(?=\</body\>\</html\>)");
It finds a string but cuts it off long before </body></html>. I escaped characters based on the RegEx cheat sheet.
What am i missing?

I'd recommend using the HtmlAgilityPack instead - parsing HTML with regular expressions is very, very fragile.
The latest version even supports Linq so you can get your content like this:
HtmlWeb web = new HtmlWeb();
HtmlDocument doc = web.Load("http://stackoverflow.com");
string html = doc.DocumentNode.Descendants("body").Single().InnerHtml;

Regex is not meant for such html handling, as many here would say. Without having your sample web page / html, I can only say that try removing the non-greedy ? quantifier in (.*?) and try. After all, a html page will have only one head and body.

Though regexes are definitely not the best tool for this task, there are a few suggestions and points I would like to make:
un-escape the angle brackets - with the # before your string, they are going through to the regex and they do not need to be escaped for a .NET regex
with your regex, you need to make sure that the head/body tag combinations do not have any white-space between them.
with your regex, the body tag cannot have any attributes.
I would suggest something more like:
(?<=</head>\s*<body(\s[^>]*)?>)(.*?)(?=</body>\s*</html>)
this seems to work for me on the source of this page!

As the others have said, the correct way to handle this is with an HTML-specific tool. I just want to point out some problems with that cheat-sheet.
First, it's wrong about angle brackets: you do not need to escape them. In fact, it's wrong twice: it also says \< and \> match word boundaries, which is both incorrect for .NET, and incompatible with the advice about escaping angle brackets.
That cheat-sheet is just a random collection of regex syntax elements; most of them will work in most flavors, but many are guaranteed not to work in your particular flavor, whatever it happens to be. I recommend you disregard it and rely instead on .NET-specific documents or Regular-Expressions.info. The books Mastering Regular Expressions and Regular Expressions Cookbook are both excellent, too.
As for your regex, I don't see how it could behave the way you say it does. If it were going to fail, I would expect it to fail completely. Does your HTML document contain a CDATA section or SGML comment with </body></html> inside it? Or is it really two or more HTML documents run together?

Regex for a string

It would be great if someone could provide me the Regular expression for the following string.
Sample 1: <div>abc</div><br>
Sample 2: <div>abc</div></div></div></div></div><br>
As you can see in the samples provided above, I need to match the string no matter how many number of </div> occurs. If there occurs any other string between </div> and <br>, say like this <div>abc</div></div></div>DEF</div></div><br> OR <div>abc</div></div></div></div></div>DEF<br>, then the Regex should not match.
Thanks in advance.

Try this:
<div>([^<]+)(?:<\/div>)*<br>
As seen on rubular
Notes:
This only works if there are not tags in the abc part (or anything that has a < symbol).
You might want to use start and end of string anchors (^<div>([^<]+)(?:<\/div>)*<br>$ if you want your string to match the pattern exactly.
If you want to allow the abc part to be empty, use * instead of +
That being said, you should be wary of using regex to parse HTML.
In this example, you can use regex because you are parsing a (hopefully) known, regular subset of HTML. But a more robust solution (ie: an [X]HTML parser like HtmlAgilityPack) is preferred when it comes to parsing HTML.

You need to use a real parser. Things like infinitely nested tags can't be handled via regex.

You could also include a named group in the the expression, e.g.:
<div>(?<text>[^<]*)(?:<\/div>)*<br>
Implemented in C#:
var regex = new Regex(#"<div>(?<text>[^<]*)(?:<\/div>)*<br>");
Func<Match, string> getGroupText = m => (m.Success && m.Groups["text"] != null) ? m.Groups["text"].Value : null;
Func<string, string> getText = s => getGroupText(regex.Match(s));
Console.WriteLine(getText("<div>abc</div><br>"));
Console.WriteLine(getText("<div>123</div></div></div></div></div><br>"));

NullUserException's answer is good. Here are a couple of questions, and variations, depending on what you want.
Do you want to prevent anything from occurring before the open div tag? If so, keep the ^ at the beginning of the regex. If not, drop it.
The rest of this post refers to the following section of the regex:
([^<]+?)
Do you want to capture the contents of the div, or just know that it matches your form? To capture, leave it as is. If you don't need to capture, drop the parentheses from the above.
Do you want to match if there is nothing inside the div? If so change the + in the above to *
Finally, although it will work fine, you don't need the ? in the above.

I think, this regex is more flexible:
<div\b[^><]*+>(?>.*?</div>)(?:\s*+</div>)*+\s*+<br(?:\s*+/)?>
I don't include the ^ and $ in the beginning and the end of my regex because we cannot assure that your sample will always in a single line.

How can I write a regular expression to capture links with no link text?

How can I write a regular expression to replace links with no link text like this:
with
http://www.somesite.com
?
This is what I was trying to do to capture the matches, and it isn't catching any. What am I doing wrong?
string pattern = "<a\\s+href\\s*=\\s*\"(?<href>.*)\">\\s*</a>";

I wouldn't use a regex - I'd use the Html Agility Pack, and a query like:
foreach(HtmlNode link in doc.DocumentElement.SelectNodes("//a[.='']")) {
link.InnerText = link.GetAttribute("href");
}

I could be wrong, but I think you simply need to change the quantifier within the href group to be lazy rather than greedy.
string pattern = #"<a\s+href\s*=\s*""(?<href>.*?)"">\s*</a>";
(I've also changed the type of the string literal to use #, for better readability.)
The rest of the regex appears fine to me. That you're not capturing any matches at all makes me think otherwise, but there could be a problem in the rest of the code (or even the input data - have you verified that?).

I would suggest
string pattern = "(<a\\b[^>]*href=\"([^\"]+)\"[^>]*>)[\\s\\r\\n]*(</a>)";
This way also links with their href attribute somewhere else would be captured.
Replace with
"$1$2$3"
The usual word of warning: HTML and regex are essentially incompatible. Use with caution, this might blow up.

Marc Gravell has the right answer, regexes are fundamentally bad at parsing HTML (see Can you provide some examples of why it is hard to parse XML and HTML with a regex? for why). See Can you provide an example of parsing HTML with your favorite parser? for examples using a variety of parsers.