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Difference between == and ===
...!= operators test for value equality for number values (e.g., NSInteger, NSUInteger, int, in Objective-C and Int, UInt, etc. in Swift). For objects (NSObject/NSNumber and subclasses in Objective-C and reference types in Swift), == and != test that the objects/reference types are the same identical t...
What is the difference between an int and a long in C++?
...which has to fit within INT_MIN and INT_MAX.
The C89 standard states that UINT_MAX should be at least 2^16-1, USHRT_MAX 2^16-1 and ULONG_MAX 2^32-1 . That makes a bit-count of at least 16 for short and int, and 32 for long. For char it states explicitly that it should have at least 8 bits (CHAR_BIT...
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
)...
No ConcurrentList in .Net 4.0?
...read-safe, limited subset of IList<T>: in particular, one that would allow an Add and provide random read-only access by index (but no Insert, RemoveAt, etc., and also no random write access).
This was the goal of my ConcurrentList<T> implementation. But when I tested its performance in...
How to make input type= file Should accept only pdf and xls
... fileReader.onload = function(e) {
var int32View = new Uint8Array(e.target.result);
//verify the magic number
// for JPG is 0xFF 0xD8 0xFF 0xE0 (see https://en.wikipedia.org/wiki/List_of_file_signatures)
if(int32View.length>4 &am...
c/c++如何判断指针无效？如NULL,0xcccccccc,0xfeeefeee,野指针等 - C/C++ -...
...BadWritePtr, IsBadReadPtr
BOOL AFXAPI AfxIsValidAddress(const void* lp, UINT nBytes,
BOOL bReadWrite /* = TRUE */)
{
// simple version using Win-32 APIs for pointer validation.
return (lp != NULL && !IsBadReadPtr(lp, nBytes) &&
(!bReadWrite || !IsBadWritePtr((LPVOID)lp, nBytes)));
}
指针...
EntityType has no key defined error
...blic
The key needs to be a CLS-compliant type, meaning unsigned types like uint, ulong etc. are not allowed.
This error can also be caused by configuration mistakes.
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Scala: List[Future] to Future[List] disregarding failed futures
...ures to a Future of List. I'm using Playframework, so ultimately, what I really want is a Future[Result] , but to make things simpler, let's just say Future[List[Int]] The normal way to do this would be to use Future.sequence(...) but there's a twist... The list I'm given usually has around 10-...
How well is Unicode supported in C++11?
...ization library
Input/output library
Regular expressions library
I think all but the first one provide terrible support. I'll get back to it in more detail after a quick detour through your other questions.
Does std::string do what it should?
Yes. According to the C++ standard, this is what ...
How do you detect where two line segments intersect? [closed]
...f r × s = 0 and (q − p) × r ≠ 0, then the two lines are parallel and non-intersecting.
If r × s ≠ 0 and 0 ≤ t ≤ 1 and 0 ≤ u ≤ 1, the two line segments meet at the point p + t r = q + u s.
Otherwise, the two line segments are not parallel but do not intersect....