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Extracting bits with a single multiplication

..... A multiplication is a bunch of shift-and-add operations. The key is to allow overflow to "shift away" the bits we don't need and put the ones we want in the right place. Multiplication by 4 (00000100) would shift everything left by 2 and get you to a00b0000 . To get the b to move up we need to...
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How do you get the logical xor of two variables in Python?

...e not comparing apples to oranges, is "if xor( isApple(x), isApple(y) )" really clearer than "if isApple(x) != isApple(y)" ? Not to me! – AmigoNico May 21 '12 at 18:27 109 ...
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Auto-center map with multiple markers in Google Maps API v3

... @MultiformeIngegno Calling it right after fitBounds worked for me in a brief test; let me know if you're still having trouble. – metadept Mar 30 '13 at 15:35 ...
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SQL Server: Query fast, but slow from procedure

... the quoted answer did not solve the problem for me. The query still ran really slow from a stored procedure. I found another answer here "Parameter Sniffing", Thanks Omnibuzz. Boils down to using "local Variables" in your stored procedure queries, but read the original for more understanding, it...
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How do I count a JavaScript object's attributes? [duplicate]

...ry object in JavaScript derives from — includes many attributes automatically, and the exact set of attributes you get depends on the particular interpreter and what code has executed before yours. So, you somehow have to separate the ones you defined from those you got "for free." Here's one way...
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Inserting multiple rows in mysql

... When loading a table from a text file, use LOAD DATA INFILE. This is usually 20 times faster than using INSERT statements. Optimizing INSERT Statements You can find more tips on how to speed up your insert statements on the link above. ...
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How can I represent an 'Enum' in Python?

...y3, e.g. you'll need __order__ in python 2). To use enum34, do $ pip install enum34 To use aenum, do $ pip install aenum Installing enum (no numbers) will install a completely different and incompatible version. from enum import Enum # for enum34, or the stdlib version # from aenum import...
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How to calculate a time difference in C++

...turns the CPU time consumed by the program. So if the program is run in parallel the time returned by the function would be the accumulated of the time spent on all CPUs, rather than the time elapsed cplusplus.com/reference/ctime/clock – Ameer Jewdaki Aug 3 '1...
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What's the difference between echo, print, and print_r in PHP?

...s, although such usage is rare; echo is slightly faster than print. (Personally, I always use echo, never print.) var_dump prints out a detailed dump of a variable, including its type and the type of any sub-items (if it's an array or an object). print_r prints a variable in a more human-readable f...
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Which $_SERVER variables are safe?

...ttacker can also control and is therefore a source of an attack. This is called a "tainted" variable, and is unsafe. 2 An...