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Programmatically find the number of cores on a machine
...umCPU = sysconf(_SC_NPROCESSORS_ONLN);
FreeBSD, MacOS X, NetBSD, OpenBSD, etc.
int mib[4];
int numCPU;
std::size_t len = sizeof(numCPU);
/* set the mib for hw.ncpu */
mib[0] = CTL_HW;
mib[1] = HW_AVAILCPU; // alternatively, try HW_NCPU;
/* get the number of CPUs from the system */
sysctl(mib, ...
How to Correctly Use Lists in R?
...where the first element is a character vector, the second is a data frame, etc. In this case, you have created two different lists. x has four vectors, each of length 1. x2 has 1 vector of length 4:
> length(x[[1]])
[1] 1
> length(x2[[1]])
[1] 4
So these are completely different lists.
R l...
JavaScript check if variable exists (is defined/initialized)
...(Assuming the variable could hold anything (string, int, object, function, etc.))
28 Answers
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Extract hostname name from string
...uld be considered the root domain (i.e. www.食狮.公司.cn, b.c.kobe.jp, etc.). Read more about it here.
Try:
npm install --save psl
Then with my "extractHostname" implementation run:
let psl = require('psl');
let url = 'http://www.youtube.com/watch?v=ClkQA2Lb_iE';
psl.get(extractHostname(url...
C# Lambda expressions: Why should I use them?
...# expressions in to the SQL expressions desired for filtering / ordering / etc. on the server side.
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notifyDataSetChanged example
I'm trying to use in my Android Application the notifyDataSetChanged() method for an ArrayAdapter but it doesn't work for me.
...
R object identification
...t(d=1:26, e=letters))
data(cars)
obj <- lm(dist ~ speed, data=cars)
..etc.
If obj is an S3 or S4 object, you can also try methods or showMethods, showClass, etc. Patrick Burns' R Inferno has a pretty good section on this (sec #7).
EDIT: Dirk and Hadley mention str(obj) in their answers. It ...
Difference between app.use and app.get in express.js
...l of them and regardless of HTTP verb used:
GET /
PUT /foo
POST /foo/bar
etc.
app.get(), on the other hand, is part of Express' application routing and is intended for matching and handling a specific route when requested with the GET HTTP verb:
GET /
And, the equivalent routing for your exa...
Why should I use IHttpActionResult instead of HttpResponseMessage?
...ide those convenient helper methods of ApiController such as Ok, NotFound, etc.
Basically, I think a class implementing IHttpActionResult as a factory of HttpResponseMessage. With that mind set, it now becomes an object that need to be returned and a factory that produces it. In general programming...
What is a JavaBean exactly?
...ytes. Those bytes can be stored in files, sent over a network connection, etc, and have enough info to allow a JVM (at least, one that knows about the object's type) to reconstruct the object later -- possibly in a different instance of the application, or even on a whole other machine!
Of course,...