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String concatenation in Ruby
...ficient in term of memory/speed from what I've seen (not measured though). All three methods will throw an uninitialized constant error when ROOT_DIR is nil.
When dealing with pathnames, you may want to use File.join to avoid messing up with pathname separator.
In the end, it is a matter of taste....
Why do people use __(double underscore) so much in C++
...specific, and are slightly more detailed than some others have suggested.
All identifiers that contain a double underscore or start with an underscore followed by an uppercase letter are reserved for the use of the implementation at all scopes, i.e. they might be used for macros.
In addition, all ...
#define macro for debug printing in C?
.... } while (0) idiom ensures that the code acts like a statement (function call). The unconditional use of the code ensures that the compiler always checks that your debug code is valid — but the optimizer will remove the code when DEBUG is 0.
If you want to work with #ifdef DEBUG, then change th...
How do I get the number of elements in a list?
...turns 3.
Explanation
Everything in Python is an object, including lists. All objects have a header of some sort in the C implementation.
Lists and other similar builtin objects with a "size" in Python, in particular, have an attribute called ob_size, where the number of elements in the object is...
Replace all non Alpha Numeric characters, New Lines, and multiple White Space with one Space
...
I marked this answer correct after all these years, because i looked back and the accepted didn't exclude underscores
– Michael Randall
Apr 12 '18 at 11:23
...
Is False == 0 and True == 1 an implementation detail or is it guaranteed by the language?
.....] Boolean values behave like the values 0 and 1, respectively, in almost all contexts, the exception being that when converted to a string, the strings "False" or "True" are returned, respectively.
There is also, for Python 2:
In numeric contexts (for example when used as the argument to an ...
How can you encode a string to Base64 in JavaScript?
... in 8 bits, it will probably break. This isn’t a problem if you’re actually treating the string as a byte array, but if you’re trying to do something else then you’ll have to encode it first.
atob() returns a “string” where each character represents an 8-bit byte – that is, its value w...
How do you generate dynamic (parameterized) unit tests in python?
...
This is called "parametrization".
There are several tools that support this approach. E.g.:
pytest's decorator
parameterized
The resulting code looks like this:
from parameterized import parameterized
class TestSequence(unittes...
The tilde operator in Python
...a unary operator (taking a single argument) that is borrowed from C, where all data types are just different ways of interpreting bytes. It is the "invert" or "complement" operation, in which all the bits of the input data are reversed.
In Python, for integers, the bits of the twos-complement repr...
Catching an exception while using a Python 'with' statement
... print 'oops'
If you want different handling for errors from the open call vs the working code you could do:
try:
f = open('foo.txt')
except IOError:
print('error')
else:
with f:
print f.readlines()
...