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Why are variables “i” and “j” used for counters?
...ation notation traditionally uses i for the first index, j for the second, and so on. Example (from http://en.wikipedia.org/wiki/Summation):
It's also used that way for collections of things, like if you have a bunch of variables x1, x2, ... xn, then an arbitrary one will be known as xi.
As...
Has reCaptcha been cracked / hacked / OCR'd / defeated / broken? [closed]
...re relate to the ineffectiveness of the concept of CAPTCHA, in principle - and while I very much agree with them, in fact gave a talk at OWASP a few months ago explaining just that - the question is very specific, so I will provide for a demonstration.
But first, I will reiterate that demonstration ...
What is the difference between ELF files and bin files?
The final images produced by compliers contain both bin file and extended loader format ELf file ,what is the difference between the two , especially the utility of ELF file.
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Passing parameters to a Bash function
...h function, but what comes up is always how to pass parameter from the command line.
7 Answers
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Understanding the Rails Authenticity Token
... a form to create, update, or destroy a resource, the Rails app creates a random authenticity_token, stores this token in the session, and places it in a hidden field in the form. When the user submits the form, Rails looks for the authenticity_token, compares it to the one stored in the session, an...
How does `scp` differ from `rsync`?
...n these tools is how they copy files.
scp basically reads the source file and writes it to the destination. It performs a plain linear copy, locally, or over a network.
rsync also copies files locally or over a network. But it employs a special delta transfer algorithm and a few optimizations to m...
Cocoa Touch: How To Change UIView's Border Color And Thickness?
... change the background color, but I'd like to also change the border color and thickness, is this possible?
14 Answers
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Difference between webdriver.Dispose(), .Close() and .Quit()
...ked in the source code for the Selenium Client & WebDriver C# Bindings and found the following.
webDriver.Close() - Close the browser window that the driver has focus of
webDriver.Quit() - Calls Dispose()
webDriver.Dispose() Closes all browser windows and safely ends the session
The ...
What's the difference between ES6 Map and WeakMap?
Looking this and this MDN pages it seems like the only difference between Maps and WeakMaps is a missing "size" property for WeakMaps. But is this true? What's the difference between them?
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What are metaclasses in Python?
In Python, what are metaclasses and what do we use them for?
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