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Core Data: Quickest way to delete all instances of an entity
...ndle the error
}
Objective-C
NSFetchRequest *request = [[NSFetchRequest alloc] initWithEntityName:@"Car"];
NSBatchDeleteRequest *delete = [[NSBatchDeleteRequest alloc] initWithFetchRequest:request];
NSError *deleteError = nil;
[myPersistentStoreCoordinator executeRequest:delete withContext:myCon...
tinyxml XML解析库下载（tinyxml2.h 和 tinyxml2.cpp） - 源码下载 - 清泛...
...>
# include <cstdarg>
#endif
/*
TODO: intern strings instead of allocation.
*/
/*
gcc:
g++ -Wall -DDEBUG tinyxml2.cpp xmltest.cpp -o gccxmltest.exe
Formatting, Artistic Style:
AStyle.exe --style=1tbs --indent-switches --break-closing-brackets --indent-preproce...
Is delete this allowed?
...as defined results, as long as (as you've noted) you assure the object was allocated dynamically, and (of course) never attempt to use the object after it's destroyed. Over the years, many questions have been asked about what the standard says specifically about delete this;, as opposed to deleting ...
C++ Singleton design pattern
... you usually do not want it to be destructed.
It will get torn down and deallocated when the program terminates, which is the normal, desired behavior for a singleton. If you want to be able to explicitly clean it, it's fairly easy to add a static method to the class that allows you to restore it ...
How to read a line from the console in C?
...ters it read. So you use fgetc:
char * getline(void) {
char * line = malloc(100), * linep = line;
size_t lenmax = 100, len = lenmax;
int c;
if(line == NULL)
return NULL;
for(;;) {
c = fgetc(stdin);
if(c == EOF)
break;
if(--len == 0)...
Is it possible to prevent an NSURLRequest from caching data or remove cached data following a reques
...e, I perform a HTTP request using NSURLRequest for a chunk of data. Object allocation spikes and I assign the data accordingly. When I finish with the data, I free it up accordingly - however instruments doesn't show any data to have been freed!
...
boost::flat_map and its performance compared to map and unordered_map
... few variations of the scenario.
A container performance is affected by:
Allocator
size of contained type
cost of implementation of copy operation, assignment operation, move operation, construction operation, of the contained type.
number of elements in the container (size of the problem)
type ha...
What's the difference between VARCHAR and CHAR?
...n hold is 255 characters.
It's 50% faster than VARCHAR.
Uses static memory allocation.
VARCHAR
Used to store variable length alphanumeric data.
The maximum this data type can hold is up to
Pre-MySQL 5.0.3: 255 characters.
Post-MySQL 5.0.3: 65,535 characters shared for the row.
It's slower tha...
How to create a memory leak in Java?
...The thread loads a class via an (optionally custom) ClassLoader.
The class allocates a large chunk of memory (e.g. new byte[1000000]), stores a strong reference to it in a static field, and then stores a reference to itself in a ThreadLocal. Allocating the extra memory is optional (leaking the clas...
How can I send mail from an iPhone application
...:
MFMailComposeViewController* controller = [[MFMailComposeViewController alloc] init];
controller.mailComposeDelegate = self;
[controller setSubject:@"My Subject"];
[controller setMessageBody:@"Hello there." isHTML:NO];
if (controller) [self presentModalViewController:controller animated:YES];
[c...