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String concatenation: concat() vs “+” operator

...then throwing it away when you create the final String. In practice memory allocation is surprisingly fast. Update: As Pawel Adamski notes, performance has changed in more recent HotSpot. javac still produces exactly the same code, but the bytecode compiler cheats. Simple testing entirely fails bec...
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How do I use IValidatableObject?

... Prop1 = 1, Prop2 = 2 }; bool validateAllProperties = false; var results = new List<ValidationResult>(); bool isValid = Validator.TryValidateObject( toValidate, new ValidationContext(toValidate, null, null), ...
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How do you calculate the average of a set of circular data? [closed]

... sum_i_from_1_to_N cos(a[i]) The method given by starblue is computationally equivalent, but his reasons are clearer and probably programmatically more efficient, and also work well in the zero case, so kudos to him. The subject is now explored in more detail on Wikipedia, and with other uses, l...
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Proper way to return JSON using node or Express

...n do this by changing the options instead. 'json replacer' JSON replacer callback, null by default 'json spaces' JSON response spaces for formatting, defaults to 2 in development, 0 in production Not actually recommended to set to 40 app.set('json spaces', 40); Then you could just respond with so...
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Why is __dirname not defined in node REPL?

... Yeah, that should really be added to the answer Eye, because that's what got me. – Tomáš Zato - Reinstate Monica Oct 12 '15 at 17:14 ...
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Python integer division yields float

... @JonathanSternberg except for all the code that was written for python 2.0. I feel like the role of / and // should be reversed to keep backwards compatibility. Also, in pretty much every other language / preserves type. i would make more sense then fo...
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Mock vs MagicMock

My understanding is that MagicMock is a superset of Mock that automatically does "magic methods" thus seamlessly providing support for lists, iterations and so on... Then what is the reason for plain Mock existing? Isn't that just a stripped down version of MagicMock that can be practically ...
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How to enable C++11/C++0x support in Eclipse CDT?

..., find the Preprocessor Include Path and go to the Providers Tab. Deselect all except CDT GCC Builtin Compiler Settings. Then untag Share settings entries … . Add the option -std=c++11 to the text box called Command to get compiler specs. Go to paths and symbols. Under Symbols, click restore defau...
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Algorithm to compare two images

...t finds 4% of positives in our test data. However, one algorithm may find all the matches, but also have a large 20% false positive rate, so there are several ways to rate your algorithms. The test data should attempt to be designed to cover as many types of dynamics as possible that you would exp...
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Execution time of C program

I have a C program that aims to be run in parallel on several processors. I need to be able to record the execution time (which could be anywhere from 1 second to several minutes). I have searched for answers, but they all seem to suggest using the clock() function, which then involves calculating...