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Double Negation in C++

...ernel). For GCC, they're implemented as follows: #define likely(cond) (__builtin_expect(!!(cond), 1)) #define unlikely(cond) (__builtin_expect(!!(cond), 0)) Why do they have to do this? GCC's __builtin_expect treats its parameters as long and not bool, so there needs to be some form of conver...
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How to run a program without an operating system?

...125\252' > main.img sudo apt-get install qemu-system-x86 qemu-system-x86_64 -hda main.img Outcome: Note that even without doing anything, a few characters are already printed on the screen. Those are printed by the firmware, and serve to identify the system. And on the T430 we just get a blank ...
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How to use the IEqualityComparer

... implement.1 In your code, the solution is to forward GetHashCode to Class_reglement.Numf.GetHashCode and implement it appropriately there. Apart from that, your Equals method is full of unnecessary code. It could be rewritten as follows (same semantics, ¼ of the code, more readable): public boo...
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What is the fastest way to send 100,000 HTTP requests in Python?

... = getStatus(url) doSomethingWithResult(status, url) q.task_done() def getStatus(ourl): try: url = urlparse(ourl) conn = httplib.HTTPConnection(url.netloc) conn.request("HEAD", url.path) res = conn.getresponse() return res.status, ourl ...
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Determine the type of an object?

... On instances of object you also have the: __class__ attribute. Here is a sample taken from Python 3.3 console >>> str = "str" >>> str.__class__ <class 'str'> >>> i = 2 >>> i.__class__ <class 'int'> >>> class...
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How to make links in a TextView clickable?

...<a> tags in the string // resource. By default these links will appear but not // respond to user input. To make them active, you need to // call setMovementMethod() on the TextView object. TextView t2 = (TextView) findViewById(R.id.text2); t2.setMovementMethod(LinkMovem...
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What is the difference between max-device-width and max-width for mobile web?

... has a browser NOT opened maximized - I suppose it is possible in a hybrid app, but that is a different case). Max-width would certainly be more universal. – Jason Jan 15 '14 at 20:34 ...
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What is the command to list the available avdnames

...ators: emulator @name-of-your-emulator where emulator is under: ${ANDROID_SDK}/tools/emulator – Dhiraj Himani Jun 16 '17 at 11:27 ...
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Detect the Internet connection is offline?

...e that the connection is lost by making failed XHR requests. The standard approach is to retry the request a few times. If it doesn't go through, alert the user to check the connection, and fail gracefully. Sidenote: To put the entire application in an "offline" state may lead to a lot of error-p...
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How to search a specific value in all tables (PostgreSQL)?

... How about dumping the contents of the database, then using grep? $ pg_dump --data-only --inserts -U postgres your-db-name > a.tmp $ grep United a.tmp INSERT INTO countries VALUES ('US', 'United States'); INSERT INTO countries VALUES ('GB', 'United Kingdom'); The same utility, pg_dump, can...