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How to check iOS version?
...system version as an indication of device or OS capabilities. There is usually a more reliable method of checking whether a particular feature or class is available.
Checking for the presence of APIs:
For example, you can check if UIPopoverController is available on the current device using NSCla...
Programmatically retrieve memory usage on iPhone
...trieve the amount of memory my iPhone app is using at anytime, programmatically. Yes I'm aware about ObjectAlloc/Leaks. I'm not interested in those, only to know if it's possible to write some code and get the amount of bytes being used and report it via NSLog.
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How to make a variadic macro (variable number of arguments)
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The reason for ## before VA_ARGS is that it swallows the preceding comma in case the variable-argument list is empty, eg. FOO("a") expands to printf("a"). This is an extension of gcc (and vc++, maybe), C99 requires at least one argument to be present in place of the elli...
What is the type of lambda when deduced with “auto” in C++11?
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The type of a lambda expression is unspecified.
But they are generally mere syntactic sugar for functors. A lambda is translated directly into a functor. Anything inside the [] are turned into constructor parameters and members of the functor object, and the parameters inside () are turned ...
Calculating a directory's size using Python?
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This walks all sub-directories; summing file sizes:
import os
def get_size(start_path = '.'):
total_size = 0
for dirpath, dirnames, filenames in os.walk(start_path):
for f in filenames:
fp = os.path.join(di...
Cartesian product of x and y array points into single array of 2D points
... 5],
[2, 5],
[3, 5]])
See Using numpy to build an array of all combinations of two arrays for a general solution for computing the Cartesian product of N arrays.
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jQuery Ajax File Upload
...ed. E.g. through FormData object, but unfortunately it is not supported by all/old browsers.
FormData support starts from following desktop browsers versions.
IE 10+
Firefox 4.0+
Chrome 7+
Safari 5+
Opera 12+
For more detail, see MDN link.
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Convert SVG image to PNG with PHP
I'm working on a web project that involves a dynamically generated map of the US coloring different states based on a set of data.
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How to limit the maximum value of a numeric field in a Django model?
...ormer can be restricted to the number of decimal places stored and the overall number of characters stored, is there any way to restrict it to storing only numbers within a certain range, e.g. 0.0-5.0 ?
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How to save an HTML5 Canvas as an image on a server?
I'm working on a generative art project where I would like to allow users to save the resulting images from an algorithm. The general idea is:
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