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Why 0 is true but false is 1 in the shell?
The above will output 1 , which is contradictory with all other programming languages I know.
10 Answers
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Where can I learn how to write C code to speed up slow R functions? [closed]
...ds C++ and Rcpp to be much more like writing R than writing C++. YMMV and all that.
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npm install vs. update - what's the difference?
What is the practical difference between npm install and npm update ? When should I use which?
5 Answers
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jQuery see if any or no checkboxes are selected
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JQuery .is will test all specified elements and return true if at least one of them matches selector:
if ($(":checkbox[name='choices']", form).is(":checked"))
{
// one or more checked
}
else
{
// nothing checked
}
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What is the difference between C# and .NET?
.... The C# specification says only a very little about the environment (basically, that it should contain some types such as int, but that's more or less all).
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JPA : How to convert a native query result set to POJO class collection
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JPA provides an SqlResultSetMapping that allows you to map whatever returns from your native query into an Entity or a custom class.
EDIT JPA 1.0 does not allow mapping to non-entity classes. Only in JPA 2.1 a ConstructorResult has been added to map return values a...
Can't append element
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Don't just use jQuery's append if you really want the element to appear in the DOM. Use the native appendChild to achieve this.
– Minqi Pan
Oct 1 '12 at 14:54
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What are database normal forms and can you give examples? [closed]
...piece of information, and there can be no duplicate rows.
2NF and 3NF are all about being dependent on the primary key. Recall that a primary key can be made up of multiple columns. As Chris said in his response:
The data depends on the key [1NF], the whole key [2NF] and nothing but the key [3NF] ...
How can I randomize the lines in a file using standard tools on Red Hat Linux?
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I'm usually a Perl fan, but came across this ruby example which has the benefit of being shorter: ruby -e 'puts STDIN.readlines.shuffle'. It would need testing on big inputs to see if the speed is comparable. (also works on OS X)
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Why don't Java Generics support primitive types?
...nerics in Java are an entirely compile-time construct - the compiler turns all generic uses into casts to the right type. This is to maintain backwards compatibility with previous JVM runtimes.
This:
List<ClassA> list = new ArrayList<ClassA>();
list.add(new ClassA());
ClassA a = list.g...