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Closed 11 years ago.
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Which type of quotes we should use in css background url (“…”)? Single, double or no quote needed?
Simple question. What quotation marks should I use in CSS?
Option #1:
background: url( 'foo.png' );
Option #2:
background: url( "foo.png" );
Both works on "normal browsers". I just want to follow the standards.
The standards say:
The format of a URI value is 'url(' followed by optional white space followed by an optional single quote (') or double quote (") character followed by the URI itself, followed by an optional single quote (') or double quote (") character followed by optional white space followed by ')'. The two quote characters must be the same.
i.e. none, single or double. If you care about IE5/Mac (which you probably don't these days) avoid ', otherwise use whatever makes you comfortable.
The standard is that you can use either for strings, and you can use either or neither for URLs. For the most part there's no real difference, but if the value you're trying to quote has double-quotes in it then it's easier to use single-quotes, and vice-versa.
Besides that, you're welcome to prefer one or the other consistently if you think it makes your files nicer and easier to edit, but nobody will shoot you for using the "wrong" one.
I use double quotes...That's how I've seen it in books and tutorials. Just be consistent in your own work
Related
For example, in Unix, a backslash (\) is a common escape character. So to escape a full stop (.) in a regular expression, one does this:
\.
But with % encoding URL parameters, we have an escape character, %, and a control code, so an ampersand (&) doesn't become:
%&
Instead, it becomes:
%26
Any reason why? Seems to just make things more complicated, on the face of it, when we could just have one escape character and a mechanism to escape itself where necessary:
%%
Then it'd be:
simpler to remember; we just need to know which characters to escape, not which to escape and what to escape them to
encoding-agnostic, as we wouldn't be sending an ASCII or Unicode representation explicitly, we'd just be sending them in the encoding the rest of the URL is going in
easy to write an encoder: s/[!\*'();:#&=+$,/?#\[\] "%-\.<>\\^_`{|}~]/%&/g (untested!)
better because we could switch to using \ as an escape character, and life would be simpler and it'd be summer all year long
I might be getting carried away now. Someone shoot me down? :)
EDIT: replaced two uses of "delimiter" with "escape character".
Percent encoding happens not only to escape delimiters, but also so that you can transport bytes that are not allowed inside URIs (such as control characters or non-ASCII characters).
I guess it's because the URL Specification and specifically the HTTP part of it, only allow certain characters so to escape those one must replace them with characters that are allowed.
Also some allowed characters have special meanings like & and ? etc
so replacing them with a control code seems the only way to solve it
If you find it hard to recognize them, bookmark this page
http://www.w3schools.com/tags/ref_urlencode.asp
I'm trying to create a RegEx Validator that checks the file extension in the FileUpload input against a list of allowed extensions (which are user specified). The following is as far as I have got, but I'm struggling with the syntax of the backward slash (\) that appears in the file path. Obviously the below is incorrect because it just escapes the (]) which causes an error. I would be really grateful for any help here. There seems to be a lot of examples out there, but none seem to work when I try them.
[a-zA-Z_-s0-9:\]+(.pdf|.PDF)$
To include a backslash in a character class, you need to use a specific escape sequence (\b):
[a-zA-Z_\s0-9:\b]+(\.pdf|\.PDF)$
Note that this might be a bit confusing, because outside of character classes, \b represents a word boundary. I also assumed, that -s was a typo and should have represented a white space. (otherwise it shouldn't compile, I think)
EDIT: You also need to escape the dots. Otherwise they will be meta character for any character but line breaks.
another EDIT: If you actually DO want to allow hyphens in filenames, you need to put the hyphen at the end of the character class. Like this:
[a-zA-Z_\s0-9:\b-]+(\.pdf|\.PDF)$
You probably want to use something like
[a-zA-Z_0-9\s:\\-]+\.[pP][dD][fF]$
which is same as
[\w\s:\\-]+\.[pP][dD][fF]$
because \w = [a-zA-Z0-9_]
Be sure character - to put as very first or very last item in the [...] list, otherwise it has special meaning for range or characters, such as a-z.
Also \ character has to be escaped by another slash, even inside of [...].
I have a string as below:
4s: and in this <em>new</em>, 5s: <em>year</em> everybody try to make our planet clean and polution free.
Replace string:
4s: and in this <em>new</em>, <em>year</em> everybody try to make our planet clean and polution free.
what i want is ,if string have two <em> tags , and if gap between these two <em> tags is of just one word and also , format of that word will be of ns: (n is any numeric value 0 to 4 char. long). then i want to remove ns: from that string. while keeping punctuation marks('?', '.' , ',',) between two <em> as it is.
also i like to add note that. input string may or may not have punctuation marks between these two <em> tags.
My regular expression as below
Regex.Replace(txtHighlight, #"</em>.(\s*)(\d*)s:(\s*).<em", "</em> <em");
Hope it is clear to my requirement.
How can I do this using regular expressions?
Not really sure what you need, but how about:
Regex.Replace(txtHighlight, #"</em>(.)\s*\d+s:\s*(.)<em", "</em>$1$2<em");
If you just want to take out the 4s 5s bit you could do something like this:
Regex.Replace(txtHighlight, #"\s\d\:", "");
This will match a space followed by a digit followed by a colon.
If that's not what you're after, my apologies. I hope it might help :)
This question already has answers here:
Are single quotes allowed in HTML?
(11 answers)
Single vs Double quotes (' vs ")
(16 answers)
Closed 5 years ago.
Is it acceptable to use single quotes around html attribute values like this:
<span class='classname'>Hi</span>
Instead of double quotes like this:
<span class="classname">Hi</span>
Who defines what's okay? W3C?
Yes, that's acceptable. It works in browsers, and it's allowed by the specifications.
The HTML5 spec says:
In the HTML syntax, attributes can be specified in four different ways:
empty attribute syntax
unquoted attribute-value syntax
single-quoted attribute-value syntax
double-quoted attribute-value syntax
The HTML4 spec says:
By default, SGML requires that all
attribute values be delimited using
either double quotation marks (ASCII
decimal 34) or single quotation marks
(ASCII decimal 39). Single quote marks
can be included within the attribute
value when the value is delimited by
double quote marks, and vice versa.
Single quotes are and have always been completely kosher, according to the W3 specification. It's a markup/code style choice, nothing more.
Yes, the W3C publishes HTML standards.
They also provide a validator at http://validator.w3.org/
the validator is ok with both for XHTML 1.0 Strict.
There is several HTML standards, so whether it’s "acceptable" entirely depends on which you're using. Furthermore collaborative projects may have a coding style which defines to use one or the other. Using " is de-facto standard, even if the HTML standard may allow ' as well.
I'm trying to complete a regular expression that will pull out matches based on their opening and closing characters, the closest I've gotten is
^(\[\[)[a-zA-Z.-_]+(\]\])
Which will match a string such as "[[word1]]" and bring me back all the matches if there is more than one, The problem is I want it to pick up matchs where there may be a space in so for example "[[word1 word2]]", now this will work if I add a space into my pattern above however this pops up a problem that it will only get one match for my entire string so for example if I have a string
"Hi [[Title]] [[Name]] [[surname]], How are you"
then the match will be [[Title]] [[Name]] [[surname]] rather than 3 matches [[Title]], [[Name]], [[surname]]. I'm sure I'm just a char or two away in the Regex but I'm stuck, How can I make it return the 3 matches.
Thanks
You just need to make you regex non-greedy by using a ? like:
^(\[\[)[a-zA-Z.-_ ]+?(\]\])
Also there is a bug in your regex. You've included - in the char class thinking of it as a literal hyphen. But - in a char class is a meta char. So it effectively will match all char between . (period) and _ (underscore). So you need to escape it as:
^(\[\[)[a-zA-Z.\-_ ]+?(\]\])
or you can put is in some other place in the regex so that it will not have things on both sides of it as:
^(\[\[)[a-zA-Z._ -]+?(\]\])
or
^(\[\[)[-a-zA-Z._ ]+?(\]\])
You need to turn off greedy matching. See these examples for different languages:
asp.net
java
javascript
You should use +? instead of +.
The one without the question mark will try to match as much as possible, while the one with the question mark as little as possible.
Another approach would be to use [^\]] as your characters instead of [a-zA-Z.-_]. That way, a match will never extend over your closing brackets.