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How to select multiple rows filled with constants?
...providable with an external variable):
SELECT level
FROM dual
CONNECT BY
level <= :n
in Oracle,
WITH q (l) AS
(
SELECT 1
UNION ALL
SELECT l + 1
FROM q
WHERE l < @n
)
SELECT l
FROM q
-- OPTION (MAXRECURSION 0)...
What's the difference between a continuation and a callback?
...ed as a simple goto (with the stack frame of the calling function replaced by the stack frame of the tail call).
Bonus: Proceeding to continuation passing style. Consider the following program:
console.log(pythagoras(3, 4));
function pythagoras(x, y) {
return x * x + y * y;
}
N...
Paging UICollectionView by cells, not screen
...ollectionView with horizontal scrolling and there are always 2 cells side-by-side per the entire screen. I need the scrolling to stop at the begining of a cell. With paging enabled, the collection view scrolls the whole page, which is 2 cells at once, and then it stops.
...
How can HTML5 “replace” Flash? [closed]
... language.
The other important thing is that the Flash player is updated by Adobe periodically to address any issues that may arise. How will they update/improve HTML5 spec if it becomes the norm and Flash went bye-bye?? They won't. You have to wait for HTML6 and all the browsers to support it. Wh...
Why is unsigned integer overflow defined behavior but signed integer overflow isn't?
Unsigned integer overflow is well defined by both the C and C++ standards. For example, the C99 standard ( §6.2.5/9 ) states
...
Why do people say there is modulo bias when using a random number generator?
...ay RAND_MAX is 10 and I decide to generate a random number between 0 and 2 by calling rand()%3. However, rand()%3 does not produce the numbers between 0 and 2 with equal probability!
When rand() returns 0, 3, 6, or 9, rand()%3 == 0. Therefore, P(0) = 4/11
When rand() returns 1, 4, 7, or 10, rand(...
How does a hash table work?
...entioned, is called a hash algorithm or hash computation and usually works by taking the data fed into it (the title of the book in this case) and calculates a number from it.
For simplicity, let's say that it just converts each letter and symbol into a number and sums them all up. In reality, it's...
Why do you have to link the math library in C?
...bc.so (or libc.a for static linking), which is linked into your executable by default (as if -lc were specified). GCC can be instructed to avoid this automatic link with the -nostdlib or -nodefaultlibs options.
The math functions in math.h have implementations in libm.so (or libm.a for static link...
What kind of virtual machine is BEAM (the Erlang VM)?
...
The Erlang VM runs as one OS process. By default it runs one OS thread per core to achieve maximum utilisation of the machine. The number of threads and on which cores they run can be set when the VM is started.
Erlang processes are implemented entirely by the E...
Concept of void pointer in C programming
...zing a function which can receive pointer and store it in void pointer and by using that void pointer we can make a generalized function..
You cannot just dereference it in a portable way, as it may not be properly aligned. It may be an issue on some architectures like ARM, where pointer to a data...