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Concatenating two lists - difference between '+=' and extend()
I've seen there are actually two (maybe more) ways to concatenate lists in Python:
One way is to use the extend() method:
9...
StringBuilder vs String concatenation in toString() in Java
...o builder?
At the point where you're concatenating in a loop - that's usually when the compiler can't substitute StringBuilder by itself.
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What are rvalues, lvalues, xvalues, glvalues, and prvalues?
...e they needed? Probably not if we wish to forfeit the new features. But to allow better optimization we should probably embrace them.
Quoting n3055:
An lvalue (so-called, historically,
because lvalues could appear on the
left-hand side of an assignment
expression) designates a function or
an obj...
Average of 3 long integers
...
This code will work, but isn't that pretty.
It first divides all three values (it floors the values, so you 'lose' the remainder), and then divides the remainder:
long n = x / 3
+ y / 3
+ z / 3
+ ( x % 3
+ y % 3
+ z % 3
)...
Google Chrome Extensions - Can't load local images with CSS
...ion that uses the content script feature to modify a website. More specifically, the background-image of said website.
8 ...
Access nested dictionary items via a list of keys?
...ist, value):
getFromDict(dataDict, mapList[:-1])[mapList[-1]] = value
All but the last element in mapList is needed to find the 'parent' dictionary to add the value to, then use the last element to set the value to the right key.
Demo:
>>> getFromDict(dataDict, ["a", "r"])
1
>>&g...
Importing files from different folder
...ere from a search engine, this is not the answer you are looking for. Typically you would structure your files into packages (see other answers) instead of modifying the search path.
By default, you can't. When importing a file, Python only searches the directory that the entry-point script is runn...
How to exit from Python without traceback?
...
If sys.exit() is called in "main program stuff", the code above throws away the value passed to sys.exit. Notice that sys.exit raises SystemExit and the variable "e" will contain the exit code.
– bstpierre
...
Why use prefixes on member variables in C++ classes
...before a capital letter in a word is reserved.
For example:
_Foo
_L
are all reserved words while
_foo
_l
are not. There are other situations where leading underscores before lowercase letters are not allowed. In my specific case, I found the _L happened to be reserved by Visual C++ 2005 and ...
Batch files - number of command line arguments
...still use shift to count more than 9 ... and without having 10 lines of equally-looking code.
– Joey
Sep 30 '09 at 13:13
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