大约有 2,400 项符合查询结果（耗时：0.0098秒） [XML]
MySQL - length() vs char_length()
... store 10 characters, which may be more than 10 bytes.
In indexes, it will allocate the maximium length of the field - so if you are using UTF8-mb4, it will allocate 40 bytes for the 10 character field.
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What's the best way to do a backwards loop in C/C#/C++?
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your array_size seems to work for statically allocated arrays, but failed for me when a was 'new int[7]' for example.
– Nate Parsons
Dec 29 '08 at 5:12
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Fastest way to check if a string matches a regexp in ruby?
...erformance enhancement in the release notes for 2.4.0, as it avoids object allocations performed by other methods such as Regexp#match and =~:
Regexp#match?
Added Regexp#match?, which executes a regexp match without creating a back reference object and changing $~ to reduce object allocation.
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Why cast an unused function parameter value to void?
...er name in the body is to avoid warnings like
unused.c: In function ‘l_alloc’:
unused.c:3:22: warning: unused parameter ‘ud’ [-Wunused-parameter]
void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
^~
This warning can be suppressed with using the actu...
Passing references to pointers in C++
...er itself, not the object to which it points. For example, a function that allocates memory and assigns the address of the memory block it allocated to its argument must take a reference to a pointer, or a pointer to pointer:
void myfunc(string*& val)
{
//val is valid even after function call
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How to print out the method name and line number and conditionally disable NSLog?
...fdef DEBUG
# define ULog(fmt, ...) { UIAlertView *alert = [[UIAlertView alloc] initWithTitle:[NSString stringWithFormat:@"%s\n [Line %d] ", __PRETTY_FUNCTION__, __LINE__] message:[NSString stringWithFormat:fmt, ##__VA_ARGS__] delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil]; [alert sh...
UIActivityViewController crashing on iOS 8 iPads
...image];
UIActivityViewController *controller = [[UIActivityViewController alloc] initWithActivityItems:postItems applicationActivities:nil];
//if iPhone
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
[self presentViewController:controller animated:YES completion:nil];
}
//if iPa...
What does the git index contain EXACTLY?
...ommit 3255089, commit abb4bb8, commit c780b9c, commit 3b1d9e0, commit 371ed0d (10 Oct 2018) by Ben Peart (benpeart).
See commit 252d079 (26 Sep 2018) by Nguyễn Thái Ngọc Duy (pclouds).
(Merged by Junio C Hamano -- gitster -- in commit e27bfaa, 19 Oct 2018)
ieot: add Index Entry Offset Table (I...
.NET List Concat vs AddRange
...ed execution, using Concat would likely be faster because it avoids object allocation - Concat doesn't copy anything, it just creates links between the lists so when enumerating and you reach the end of one it transparently takes you to the start of the next!
– Greg Beech
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Why is an int in OCaml only 31 bits?
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See the the "representation of integers, tag bits, heap-allocated values" section of https://ocaml.org/learn/tutorials/performance_and_profiling.html for a good description.
The short answer is that it is for performance. When passing an argument to a function it is either passe...