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HTML: Include, or exclude, optional closing tags?
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The optional ones are all ones that should be semantically clear where they end, without needing the end tag.
E.G. each <li> implies a </li> if there isn't one right before it.
The forbidden end tags all would be immediately followe...
How to create empty data frame with column names specified in R? [duplicate]
I need to create an empty data frame in R with specified column names. Any simplest way ?
2 Answers
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string.charAt(x) or string[x]?
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Bracket notation now works on all major browsers, except for IE7 and below.
// Bracket Notation
"Test String1"[6]
// charAt Implementation
"Test String1".charAt(6)
It used to be a bad idea to use brackets, for these reasons (Source):
This notatio...
What is the difference between require() and library()?
...uld add this:
It is probably best to avoid using require() unless you actually will be using the value it returns e.g in some error checking loop such as given by thierry.
In most other cases it is better to use library(), because this will give an error message at package loading time if the pack...
What is the correct way to restore a deleted file from SVN?
...ember, the result doesn't count until you commit it. You can revert if it all goes haywire.
– gbarry
Jan 29 '09 at 5:08
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How to remove leading and trailing zeros in a string? Python
I have several alphanumeric strings like these
6 Answers
6
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Can you set a border opacity in CSS?
...wsers do not understand the rgba format and will not display any border at all if this is the entire declaration. The solution is to provide two border declarations. The first with a fake opacity, and the second with the actual. If a browser is capable, it will use the second, if not, it will use th...
Regexp Java for password validation
...ecial character must occur at least once
(?=\S+$) # no whitespace allowed in the entire string
.{8,} # anything, at least eight places though
$ # end-of-string
It's easy to add, modify or remove individual rules, since every rule is an independent "module".
Th...
Regular expression for floating point numbers
...ssues in some languages (like Java).
Thanks to the nameless one for originally recognizing this.
One relatively simple pattern for matching a floating point number is
[+-]?([0-9]*[.])?[0-9]+
This will match:
123
123.456
.456
See a working example
If you also want to match 123. (a period w...
How to check if element in groovy array/hash/collection/list?
How do I figure out if an array contains an element?
I thought there might be something like [1, 2, 3].includes(1) which would evaluate as true .
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