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How to count the number of set bits in a 32-bit integer?
... CPU you are on and what your usage pattern is.
Some CPUs have a single built-in instruction to do it and others have parallel instructions which act on bit vectors. The parallel instructions (like x86's popcnt, on CPUs where it's supported) will almost certainly be fastest. Some other architecture...
Get a list of resources from classpath directory
...urce names from a given classpath directory, something like a method List<String> getResourceNames (String directoryName) .
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Aggregate / summarize multiple variables per group (e.g. sum, mean)
...data frame, is there a easy way to aggregate ( sum , mean , max et c) multiple variables simultaneously?
8 Answers
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Is there any difference between DECIMAL and NUMERIC in SQL Server?
...rences a column in "NUMERIC(18,0)" format, you will get the error Column '<referencedColumn>' is not the same data type as referencing column '<parentTable>.<parentColumn>' in foreign key '<yourKeyName>'. They have to both be NUMERIC(x,y), or both be DECIMAL(x,y).
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How to rename files and folder in Amazon S3?
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I just tested this and it works:
aws s3 --recursive mv s3://<bucketname>/<folder_name_from> s3://<bucket>/<folder_name_to>
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Why does Stream not implement Iterable?
In Java 8 we have the class Stream<T> , which curiously have a method
9 Answers
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What is the logic behind the “using” keyword in C++?
...eally good idea but might not have traction because it would be too difficult to implement, too confusing, or would contradict old code.
Here is an old paper from 2003 n1449. The rationale seems to be related to templates. Warning: there may be typos due to copying over from PDF.
First let’s con...
How can I convert a hex string to a byte array? [duplicate]
Can we convert a hex string to a byte array using a built-in function in C# or do I have to make a custom method for this?
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New features in java 7
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break;
case "baz":
processBaz(s);
// fall-through
default:
processDefault(s);
break;
}
Binary literals
int binary = 0b1001_1001;
Improved Type Inference for Generic Instance Creation
Map<String, List<String>> anagrams = new HashMap<String, List<Str...
Rerender view on browser resize with React
...owDimensions(props) {
const [width, height] = useWindowSize();
return <span>Window size: {width} x {height}</span>;
}
The advantage here is the logic is encapsulated, and you can use this Hook anywhere you want to use the window size.
Using React classes:
You can listen in compon...