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Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_
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Culprit: False Data Dependency (and the compiler isn't even aware of it)
On Sandy/Ivy Bridge and Haswell processors, the instruction:
popcnt src, dest
appears to have a false dependency on the destination register dest. Even though the instruction only...
Querying DynamoDB by date
I'm coming from a relational database background and trying to work with amazon's DynamoDB
7 Answers
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Generate a Hash from string in Javascript
...same as hash * 31 + char but a LOT faster. It's nice because it's so fast, and 31 is a small prime. Win win there.
– corsiKa
Sep 30 '11 at 21:59
43
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What are the use(s) for tags in Go?
...ues of struct fields. Basically we need to acquire the Type of our struct, and then we can query fields e.g. with Type.Field(i int) or Type.FieldByName(name string). These methods return a value of StructField which describes / represents a struct field; and StructField.Tag is a value of type Struct...
Way to get number of digits in an int?
...thematically, numbers don't have a length, nor do they have digits. Length and digits are both properties of a physical representation of a number in a specific base, i.e. a String.
A logarithm-based solution does (some of) the same things the String-based one does internally, and probably does so ...
Highlight a word with jQuery
...ipt-text-higlighting-jquery-plugin.html
*
* Code a little bit refactored and cleaned (in my humble opinion).
* Most important changes:
* - has an option to highlight only entire words (wordsOnly - false by default),
* - has an option to be case sensitive (caseSensitive - false by default)
* ...
Removing multiple keys from a dictionary safely
... it might be more efficient to use for key in set(the_dict) & entries: and bypass the key in dict test.
– DylanYoung
Apr 15 at 15:30
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Performance difference for control structures 'for' and 'foreach' in C#
...corlib]System.IDisposable::Dispose()
IL_002f: endfinally
} // end handler
IL_0030: ret
} // end of method Test::IterateOverList
The compiler treats arrays differently, converting a foreach loop basically to a for loop, but not List<T>. Here's the equivalent code for an array:
sta...
EF5: Cannot attach the file ‘{0}' as database '{1}'
...alDB. Sometimes it fixes it to delete the DB. You can do this from the command line.
Open the "Developer Command Propmpt for VisualStudio" under your start/programs menu.
Run the following commands:
sqllocaldb.exe stop v11.0
sqllocaldb.exe delete v11.0
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Test if lists share any items in python
... generally the fastest.
There are four common ways to test if two lists a and b share any items. The first option is to convert both to sets and check their intersection, as such:
bool(set(a) & set(b))
Because sets are stored using a hash table in Python, searching them is O(1) (see here for...