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Value of i for (i == -i && i != 0) to return true in Java
...000000000000000000
Taking the negative value is done by first swapping 0 and 1, which gives
01111111111111111111111111111111
and by adding 1, which gives
10000000000000000000000000000000
As you can see in the link I gave, Wikipedia mentions the problem with the most negative numbers and spec...
What's a concise way to check that environment variables are set in a Unix shell script?
...(an empty string) is OK — not exactly what you want, but the alternative and older notation.
The second variant (using :?) requires DEST to be set and non-empty.
If you supply no message, the shell provides a default message.
The ${var?} construct is portable back to Version 7 UNIX and the Bourne ...
Regular expression to match a word or its prefix
...
Square brackets are meant for character class, and you're actually trying to match any one of: s, |, s (again), e, a, s (again), o and n.
Use parentheses instead for grouping:
(s|season)
or non-capturing group:
(?:s|season)
Note: Non-capture groups tell the engin...
Export/import jobs in Jenkins
...ig from the Jenkins Configuration Page.
Update 2020.03.10
The JenkinsCI landscape has changed a lot... I've been using Job DSL for a while now.
We have a SEED Job that generates the rest of the jobs.
This helps us both recreate or move for the Jenkins server whenever needed :)
You could also vers...
How to rename with prefix/suffix?
...
In Bash and zsh you can do this with Brace Expansion. This simply expands a list of items in braces. For example:
# echo {vanilla,chocolate,strawberry}-ice-cream
vanilla-ice-cream chocolate-ice-cream strawberry-ice-cream
So you ...
JavaScript and Threads
...ol API
WHATWG has a Draft Recommendation for worker threads: Web Workers
And there's also Mozilla’s DOM Worker Threads
Update: June 2009, current state of browser support for JavaScript threads
Firefox 3.5 has web workers. Some demos of web workers, if you want to see them in action:
Simu...
Lambda capture as const reference?
...entifier
& identifier
this
The text only mention capture-by-copy and capture-by-reference and doesn't mention any sort of const-ness.
Feels like an oversight to me, but I haven't followed the standardization process very closely.
...
Replacing blank values (white space) with NaN in pandas
I want to find all values in a Pandas dataframe that contain whitespace (any arbitrary amount) and replace those values with NaNs.
...
What does “S3 methods” mean in R?
Since I am fairly new to R, I do not know what the S3 methods and objects are. I found that there are S3 and S4 object systems, and some recommend to use S3 over S4 if possible (See Google's R Style Guide at http://google-styleguide.googlecode.com/svn/trunk/google-r-style.html )*. However, I do not...
How to find out what type of a Mat object is with Mat::type() in OpenCV
...
Here is a handy function you can use to help with identifying your opencv matrices at runtime. I find it useful for debugging, at least.
string type2str(int type) {
string r;
uchar depth = type & CV_MAT_DEPTH_MASK;
uchar cha...