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Efficient Algorithm for Bit Reversal (from MSB->LSB to LSB->MSB) in C
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NOTE: All algorithms below are in C, but should be portable to your language of choice (just don't look at me when they're not as fast :)
Options
Low Memory (32-bit int, 32-bit machine)(from here):
unsigned int
reverse(register ...
Remove last item from array
..., -1) will not. Pop is of course faster but may not be always suitable for all needs.
– adelriosantiago
Sep 23 '17 at 0:40
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Is inline assembly language slower than native C++ code?
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Yes, most times.
First of all you start from wrong assumption that a low-level language (assembly in this case) will always produce faster code than high-level language (C++ and C in this case). It's not true. Is C code always faster than Java code? N...
Why is there no xrange function in Python3?
...Some performance measurements, using timeit instead of trying to do it manually with time.
First, Apple 2.7.2 64-bit:
In [37]: %timeit collections.deque((x for x in xrange(10000000) if x%4 == 0), maxlen=0)
1 loops, best of 3: 1.05 s per loop
Now, python.org 3.3.0 64-bit:
In [83]: %timeit collec...
What is the best regular expression to check if a string is a valid URL?
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I wrote my URL (actually IRI, internationalized) pattern to comply with RFC 3987 (http://www.faqs.org/rfcs/rfc3987.html). These are in PCRE syntax.
For absolute IRIs (internationalized):
/^[a-z](?:[-a-z0-9\+\.])*:(?:\/\/(?:(?:%[0-9a-f][0-9a-f]...
How do I safely pass objects, especially STL objects, to and from a DLL?
How do I pass class objects, especially STL objects, to and from a C++ DLL?
4 Answers
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MemoryCache does not obey memory limits in configuration
...ximum cache size, but in my tests it does not appear that the cache is actually obeying the limits.
7 Answers
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Detecting Unsaved Changes
...reunload methods as required.
From the comments, the following references all input fields, without duplicating code:
$(':input').change(function () {
Using $(":input") refers to all input, textarea, select, and button elements.
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How do you 'redo' changes after 'undo' with Emacs?
...ven a navigation command such as C-f) after a sequence of undo operations, all the undos are pushed on to the operation stack. So the next undo undoes the last command. Suppose you do have an operation sequence that looks like this:
Insert "foo"
Insert "bar"
Insert "I love spam"
Now, you undo....
Android: upgrading DB version and adding new table
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1. About onCreate() and onUpgrade()
onCreate(..) is called whenever the app is freshly installed. onUpgrade is called whenever the app is upgraded and launched and the database version is not the same.
2. Incrementing the db version
You need a constructor like:
MyOpenHelp...