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Why should the copy constructor accept its parameter by reference in C++?
... reference, it's by value. To do that you make a copy, and to do that you call the copy constructor. But to do that, we need to make a new value, so we call the copy constructor, and so on...
(You would have infinite recursion because "to make a copy, you need to make a copy".)
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git still shows files as modified after adding to .gitignore
...re saying that you need to commit after removing the cached files? That really seems counter-intuitive; these are files I do NOT want to commit. And I do not want them deleted from the repository (I just want them to no longer be hanging around cluttering my git status). Or am I just really confu...
What are the mathematical/computational principles behind this game?
My kids have this fun game called Spot It! The game constraints (as best I can describe) are:
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How do RVM and rbenv actually work?
I am interested in how RVM and rbenv actually work.
5 Answers
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change text of button and disable button in iOS
...antage of the fact that they are passed in as an argument to the IBAction calls:
- (IBAction) triggerActionWithSender: (id) sender;
This can be bound to the button and you’ll get the button in the sender argument when the action is triggered. If that’s not enough (because you need to access t...
jQuery: checking if the value of a field is null (empty)
...ype]').val().length != 0){}
If you want to check if the element exist at all, you should do that before calling val:
var $d = $('#person_data[document_type]');
if ($d.length != 0) {
if ($d.val().length != 0 ) {...}
}
s...
What is Linux’s native GUI API?
...heir own APIs to handle windows, events and other OS stuff. I have never really got a clear answer as to what Linux’s equivalent is?
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Imitate Facebook hide/show expanding/contracting Navigation Bar
...OS7 Facebook iPhone app, when the user scrolls up the navigationBar gradually hides itself to a point where it completely vanishes. Then when the user scrolls down the navigationBar gradually shows itself.
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Expand/collapse section in UITableView in iOS
...LOOK like a header, and setup the tableView:didSelectRowAtIndexPath to manually expand or collapse the section it is in.
I'd store an array of booleans corresponding the the "expended" value of each of your sections. Then you could have the tableView:didSelectRowAtIndexPath on each of your custom h...
How to set size for local image using knitr for markdown?
... using this function is that it is portable in the sense that it works for all document formats that knitr supports, so you do not need to think if you have to use, for example, LaTeX or Markdown syntax, to embed an external image. Chunk options related to graphics output that work for normal R plot...