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Designing function f(f(n)) == -n
...sitive integer will overflow, so it will work for all integers except that one.
To make it work for real numbers you need to replace the n in (-1)n with { ceiling(n) if n>0; floor(n) if n<0 }.
In C# (works for any double, except in overflow situations):
static double F(double n)
{
if ...
How to make an Android device vibrate?
...(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
v.vibrate(VibrationEffect.createOneShot(500, VibrationEffect.DEFAULT_AMPLITUDE));
} else {
//deprecated in API 26
v.vibrate(500);
}
Note:
Don't forget to include permission in AndroidManifest.xml file:
<uses-permission andro...
Which Java Collection should I use?
...
Since I couldn't find a similar flowchart I decided to make one myself.
This flow chart does not try and cover things like synchronized access, thread safety etc or the legacy collections, but it does cover the 3 standard Sets, 3 standard Maps and 2 standard Lists.
This image was ...
How to redirect all HTTP requests to HTTPS
...as issues for me on certain URLs. For example, http://server/foo?email=someone%40example.com redirects to https://server/foo?email=someone%2540example.com i.e. the "@" sign gets URL-quoted twice. Using the method in @ssc's answer does not have this issue.
– psmears
...
How do I merge changes to a single file, rather than merging commits?
...l merge all of your changes, but we are only using this branch to grab the one file.
Fix up any Conflicts etc. investigate your file.
checkout your working branch
Checkout the file commited from your merge.
Commit it.
I tried patching and my situation was too ugly for it. So in short it would loo...
When should I use Debug.Assert()?
...uild your project in Release mode, all validations/error-checking will be gone.
– Oscar Mederos
May 7 '11 at 8:31
28
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Ruby: Can I write multi-line string with no concatenation?
...eeded (easy multi-line concatenation WITHOUT extra whitespace), but since none of the actual answers had it, I'm compiling them here:
str = 'this is a multi-line string'\
' using implicit concatenation'\
' to prevent spare \n\'s'
=> "this is a multi-line string using implicit concatenation ...
Single vs Double quotes (' vs ")
...
I suggest though single over double -- Why use two when one can do the job.
– Ujjwal Singh
Jun 22 '14 at 19:00
3
...
Is “for(;;)” faster than “while (TRUE)”? If not, why do people use it?
...es are only worth your time for things that really matter. This just isn't one of those things. As you can see, everyone has a pet way of writing an unending loop. Pick for yourself whatever makes you happiest for the little things, and then run your profiler on the code that matters. :)
...
How to atomically delete keys matching a pattern using Redis
...0, you can run lua scripts, which execute atomically. I have never written one, but I think it would look something like this
EVAL "return redis.call('del', unpack(redis.call('keys', ARGV[1])))" 0 prefix:[YOUR_PREFIX e.g delete_me_*]
Warning: As the Redis document says, because of performance ...