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Difference between dispatch_async and dispatch_sync on serial queue?
...k is finished whereas dispatch_async return after it is added to the queue and may not finished.
for this code
dispatch_async(_serialQueue, ^{ printf("1"); });
printf("2");
dispatch_async(_serialQueue, ^{ printf("3"); });
printf("4");
It may print 2413 or 2143 or 1234 but 1 always before 3
for ...
Switch statement: must default be the last case?
...
The C99 standard is not explicit about this, but taking all facts together, it is perfectly valid.
A case and default label are equivalent to a goto label. See 6.8.1 Labeled statements. Especially interesting is 6.8.1.4, which enables...
How to concatenate twice with the C preprocessor and expand a macro as in “arg ## _ ## MACRO”?
...
Standard C Preprocessor
$ cat xx.c
#define VARIABLE 3
#define PASTER(x,y) x ## _ ## y
#define EVALUATOR(x,y) PASTER(x,y)
#define NAME(fun) EVALUATOR(fun, VARIABLE)
extern void NAME(mine)(char *x);
$ gcc -E xx.c
# 1 "xx.c"
# ...
Android studio, gradle and NDK
I am very new to this whole gradle and Android Studio support. I have managed to convert my android project to gradle using the export option.
...
Does Java 8 provide a good way to repeat a value or function?
...- 1)
.forEach(System.out::println);
Or build a custom iteration and limit the size of the iteration:
IntStream.iterate(1, i -> i + 2)
.limit(8)
.forEach(System.out::println);
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Android emulator-5554 offline
... order to be assured that your emulator starts working again :
Go to cmd and type adb kill-server
Go to task manager and find adb in processes. If you find one, right click on it and click on end process tree.
In eclipse, go to Window>Android Virtual Device Manager, click on the AVD you want t...
Codeigniter - no input file specified
I am a beginner in Codeigniter and I saw a CI tutorial and was just trying to do a simple thing. I downloaded the CI and added this file to controller directory, but it won't work.
...
Confusion between factor levels and factor labels
There seems to be a difference between levels and labels of a factor in R.
Up to now, I always thought that levels were the 'real' name of factor levels, and labels were the names used for output (such as tables and plots). Obviously, this is not the case, as the following example shows:
...
Replace all non Alpha Numeric characters, New Lines, and multiple White Space with one Space
...would be [\W_]
text.replace(/[\W_]+/g," ");
\W is the negation of shorthand \w for [A-Za-z0-9_] word characters (including the underscore)
Example at regex101.com
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Retina displays, high-res background images
...wer, here is the retina detection query I tend to use:
@media
only screen and (-webkit-min-device-pixel-ratio: 2),
only screen and ( min--moz-device-pixel-ratio: 2),
only screen and ( -o-min-device-pixel-ratio: 2/1),
only screen and ( min-device-pixel-ratio: 2),
only screen and ( ...