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What is “:-!!” in C code?

...sizeof(struct { int: -!!(e); })) (e): Compute expression e. !!(e): Logically negate twice: 0 if e == 0; otherwise 1. -!!(e): Numerically negate the expression from step 2: 0 if it was 0; otherwise -1. struct{int: -!!(0);} --> struct{int: 0;}: If it was zero, then we declare a struct with an an...
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Multiple levels of 'collection.defaultdict' in Python

...ng specific that you need help with? When d[new_key] is accessed, it will call the lambda which will create a new defaultdict(int). And when d[existing_key][new_key2] is accessed, a new int will be created. – interjay Oct 11 '13 at 12:53 ...
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TypeError: module.__init__() takes at most 2 arguments (3 given)

...named Object.py . When I try to inherit from this class in another file, calling the constructor throws an exception: 5 An...
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Return a value if no rows are found in Microsoft tSQL

... S.Id = @SiteId and S.Status = 1 AND (S.WebUserId = @WebUserId OR S.AllowUploads = 1) share | improve this answer | follow | ...
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Python argparse: How to insert newline in the help text?

...nfortunately Only the name of this class is considered a public API. All the methods provided by the class are considered an implementation detail. So probably not a great idea, although it might not matter, since 2.7 is meant to be the last 2.x python and you'll be expected to refactor lots ...
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Migrating from JSF 1.2 to JSF 2.0

... JSP 2.x If you're using JSP 2.x and want to keep using it, then you basically don't need to change anything else. Gradually upgrading If you're already using a suffix url-pattern for the FacesServlet, like *.jsf, then it's good to know that the FacesServlet will first scan for *.xhtml file and ...
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What is the difference between '/' and '//' when used for division?

...floating point division, and the latter is floor division, sometimes also called integer division. In Python 2.2 or later in the 2.x line, there is no difference for integers unless you perform a from __future__ import division, which causes Python 2.x to adopt the 3.x behavior. Regardless of the ...
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What's the difference between dist-packages and site-packages?

I'm a bit miffed by the python package installation process. Specifically, what's the difference between packages installed in the dist-packages directory and the site-packages directory? ...
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How do you detect where two line segments intersect? [closed]

...f r × s = 0 and (q − p) × r ≠ 0, then the two lines are parallel and non-intersecting. If r × s ≠ 0 and 0 ≤ t ≤ 1 and 0 ≤ u ≤ 1, the two line segments meet at the point p + t r = q + u s. Otherwise, the two line segments are not parallel but do not intersect....
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How can I force division to be floating point? Division keeps rounding down to 0?

... a floating point number in Python in the following? c = a / b What is really being asked here is: "How do I force true division such that a / b will return a fraction?" Upgrade to Python 3 In Python 3, to get true division, you simply do a / b. >>> 1/2 0.5 Floor division, the classic di...