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In log4j, does checking isDebugEnabled before logging improve performance?
...e when it involves invocation of the toString() methods of various objects and concatenating the results.
In the given example, the log message is a constant string, so letting the logger discard it is just as efficient as checking whether the logger is enabled, and it lowers the complexity of the ...
Unnamed/anonymous namespaces vs. static functions
...
The C++ Standard reads in section 7.3.1.1 Unnamed namespaces, paragraph 2:
The use of the static keyword is
deprecated when declaring objects in a
namespace scope, the unnamed-namespace
provides a superior alternative.
...
PHP - Get bool to echo false when false
...ed Feb 9 '11 at 18:05
Dan GrossmanDan Grossman
48.1k1010 gold badges100100 silver badges9494 bronze badges
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Modulo operator with negative values [duplicate]
...rom ISO14882:2011(e) 5.6-4:
The binary / operator yields the quotient, and the binary % operator
yields the remainder from the division of the first expression by the
second. If the second operand of / or % is zero the behavior is
undefined. For integral operands the / operator yields the ...
How to remove focus border (outline) around text/input boxes? (Chrome) [duplicate]
...r elements such as DIV's used as modals. To prevent the highlight on those and all other elements as well, you can do:
*:focus {
outline: none;
}
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Operation on every pair of element in a list
...x, y)
Edit: There are two very similar functions as well, permutations() and combinations(). To illustrate how they differ:
product() generates every possible pairing of elements, including all duplicates:
1,1 1,2 1,3 1,4
2,1 2,2 2,3 2,4
3,1 3,2 3,3 3,4
4,1 4,2 4,3 4,4
permutation...
Erasing elements from a vector
...ranteed to occur only once in the vector. It may be present multiple times and I need to clear all of them. My code is something like this:
...
What is pseudopolynomial time? How does it differ from polynomial time?
...
To understand the difference between polynomial time and pseudopolynomial time, we need to start off by formalizing what "polynomial time" means.
The common intuition for polynomial time is "time O(nk) for some k." For example, select...
How to use Greek symbols in ggplot2?
My categories need to be named with Greek letters. I am using ggplot2 , and it works beautifully with the data. Unfortunately I cannot figure out how to put those greek symbols on the x axis (at the tick marks) and also make them appear in the legend. Is there any way to do it?
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Why is iterating through a large Django QuerySet consuming massive amounts of memory?
...QuerySet in the following ways:
Iteration. A QuerySet is iterable, and it executes its database query the first time you iterate over it. For example, this will print the headline of all entries in the database:
for e in Entry.objects.all():
print e.headline
So your ten million ro...