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What is the difference between Θ(n) and O(n)?
...e of the algorithm as n gets larger is at most proportional to g(n).
Normally, even when people talk about O(g(n)) they actually mean Θ(g(n)) but technically, there is a difference.
More technically:
O(n) represents upper bound. Θ(n) means tight bound.
Ω(n) represents lower bound.
...
Are JavaScript strings immutable? Do I need a “string builder” in JavaScript?
...ved would be the fastest way, though I kept thinking that adding a method call may make it slower...
function StringBuilder() {
this._array = [];
this._index = 0;
}
StringBuilder.prototype.append = function (str) {
this._array[this._index] = str;
this._index++;
}
StringBuilder.pro...
How to check whether a variable is a class or not?
...
The inspect.isclass is probably the best solution, and it's really easy to see how it's actually implemented
def isclass(object):
"""Return true if the object is a class.
Class objects provide these attributes:
__doc__ documentation string
__module__ ...
How to convert a string to lower case in Bash?
...ous ways:
POSIX standard
tr
$ echo "$a" | tr '[:upper:]' '[:lower:]'
hi all
AWK
$ echo "$a" | awk '{print tolower($0)}'
hi all
Non-POSIX
You may run into portability issues with the following examples:
Bash 4.0
$ echo "${a,,}"
hi all
sed
$ echo "$a" | sed -e 's/\(.*\)/\L\1/'
hi all
# t...
CSV API for Java [closed]
Can anyone recommend a simple API that will allow me to use read a CSV input file, do some simple transformations, and then write it.
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Get list of all routes defined in the Flask app
... with the @app.route('/...') decorator. Is there a way to get a list of all the routes that have been declared throughout my app? Perhaps there is some method I can call on the app object?
...
How to show all parents and subclasses of a class in IntelliJ IDEA?
...r is over a class variable, I can do Ctrl + T to have a popup that shows all its parents and subclasses. What is the equivalent in IntelliJ?
...
Is Java “pass-by-reference” or “pass-by-value”?
...
Java is always pass-by-value.
Unfortunately, we never handle an object at all, instead juggling object-handles called references (which are passed by value of course). The chosen terminology and semantics easily confuse many beginners.
It goes like this:
public static void main(String[] args) {
...
Navigation in django
...
I like this idea a lot, especially for flexibility, but it comes with the less-DRY trade-off. I did start using this in a site though.
– anonymous coward
Sep 22 '09 at 14:47
...
Check if PHP session has already started
I have a PHP file that is sometimes called from a page that has started a session and sometimes from a page that doesn't have session started. Therefore when I have session_start() on this script I sometimes get the error message for "session already started". For that I've put these lines:
...