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Why are Where and Select outperforming just Select?
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Select iterates once over the entire set and, for each item, performs a conditional branch (checking for validity) and a + operation.
Where+Select creates an iterator that skips invalid elements (doesn't yield them), performing a + only on the valid items.
So, the...
Remove last character from C++ string
...is to use the function that is intended for this task, it's called erase() and the code is: st.erase(st.size()-1). This would be called a "mutating version".
– Czarek Tomczak
Jan 19 '13 at 14:46
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How to clear basic authentication details in chrome
...th. I now want to remove the basic authentication details from the browser and try a different login.
20 Answers
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how to get the cookies from a php curl into a variable
...at this is the right answer. I think its ridiculous that curl can't just hand me a mapped array though.
– thirsty93
May 22 '09 at 15:26
3
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Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.
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Update
data.table v1.9.6+ now supports OP's original attempt and the following answer is no longer necessary.
You can use DT[order(-rank(x), y)].
x y v
1: c 1 7
2: c 3 8
3: c 6 9
4: b 1 1
5: b 3 2
6: b 6 3
7: a 1 4
8: a 3 5
9: a 6 6
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What's the foolproof way to tell which version(s) of .NET are installed on a production Windows Serv
...u should open up IE on the server for which you are looking for this info, and go to this site: http://www.hanselman.com/smallestdotnet/
That's all it takes.
The site has a script that looks your browser's "UserAgent" and figures out what version (if any) of the .NET Framework you have (or don't h...
How do I reattach to a detached mosh session?
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Mosh: You have a detached Mosh session on this server (mosh [12345]).
And can run this command:
kill 12345
Also, to close all mosh connections you can:
kill `pidof mosh-server`
Note that if you are currently connected via mosh, this last command will also disconnect you.
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How do I retrieve an HTML element's actual width and height?
... the browser's display (viewport). To do so, I need to calculate the width and height of the <div> element.
14 Ans...
How exactly does CMake work?
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The secret is that you don't have to understand what the generated files do.
CMake introduces a lot of complexity into the build system, most of which only pays off if you use it for building complex software projects.
The good news is that CMake does a good job of k...
how to install gcc on windows 7 machine?
I have MinGW on my windows 7 machine. I wish to install and use complete gcc for C compiler. I found there is no single pre-compiled ready-made installation file for this purpose. I checked the following page : http://gcc.gnu.org/install/
It is difficult and I find it above my level of understandi...