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How do you know when to use fold-left and when to use fold-right?
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You can transfer a fold into an infix operator notation (writing in between):
This example fold using the accumulator function x
fold x [A, B, C, D]
thus equals
A x B x C x D
Now you just have to reason about the associativity of your operator (by puttin...
Current time formatting with Javascript
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A JavaScript Date has several methods allowing you to extract its parts:
getFullYear() - Returns the 4-digit year
getMonth() - Returns a zero-based integer (0-11) representing the month of the year.
getDate() - Returns the day of the month (1-31).
getDay() - Returns the day of t...
Explain the encapsulated anonymous function syntax
Can you explain the reasoning behind the syntax for encapsulated anonymous functions in JavaScript? Why does this work: (function(){})(); but this doesn't: function(){}(); ?
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Get the client's IP address in socket.io
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@GarciadelCastillo you are behind a proxy probably. try this: stackoverflow.com/a/11187053/971459
– Samson
Jun 25 '13 at 9:30
4
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How to check that an element is in a std::set?
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The typical way to check for existence in many STL containers such as std::map, std::set, ... is:
const bool is_in = container.find(element) != container.end();
share
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Can't update Macports (with Mac OS X Mavericks)
After upgrading Mac OS X to newest version Mavericks, I attempted to selfupdate my Macports, but it failed:
9 Answers
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What does T&& (double ampersand) mean in C++11?
...velopers.
CAUTION: the linked article on MSDN ("Rvalue References: C++0x Features in VC10, Part 2") is a very clear introduction to Rvalue references, but makes statements about Rvalue references that were once true in the draft C++11 standard, but are not true for the final one! Specifically, i...
How do I exchange keys with values in a dictionary?
... While this seems to be correct, its really good to add an explanation of how it works rather than just the code.
– Will
Sep 10 '15 at 19:49
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The written versions of the logical operators
...test program in NetBeans, I got the red underlining as if there was a syntax error and figured the website was wrong, but it is NetBeans which is wrong because it compiled and ran as expected.
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Storing Python dictionaries
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Pickle save:
try:
import cPickle as pickle
except ImportError: # Python 3.x
import pickle
with open('data.p', 'wb') as fp:
pickle.dump(data, fp, protocol=pickle.HIGHEST_PROTOCOL)
See the pickle module documentation for additional information regarding the pr...