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iPhone: Detecting user inactivity/idle time since last screen touch
... touch or an Ended touch, to reduce the number of timer resets.
NSSet *allTouches = [event allTouches];
if ([allTouches count] > 0) {
// allTouches count only ever seems to be 1, so anyObject works here.
UITouchPhase phase = ((UITouch *)[allTouches anyObject]).phase;
...
std::string to char*
...
It won't automatically convert (thank god). You'll have to use the method c_str() to get the C string version.
std::string str = "string";
const char *cstr = str.c_str();
Note that it returns a const char *; you aren't allowed to change the...
How can I convert an RGB image into grayscale in Python?
...
SciPy's image I/O is literally PIL/Pillow. Hence, testing SciPy is effectively retesting PIL/Pillow with negligible overhead introduced by SciPy's wrapper functions. It would have been much more useful to substitute OpenCV (which does not leverage PIL...
Why does integer overflow on x86 with GCC cause an infinite loop?
...efined behavior, it means it. Anything can happen. "Anything" includes "usually integers wrap around, but on occasion weird stuff happens".
Yes, on x86 CPUs, integers usually wrap the way you expect. This is one of those exceptions. The compiler assumes you won't cause undefined behavior, and optim...
Algorithm to compare two images
...t finds 4% of positives in our test data. However, one algorithm may find all the matches, but also have a large 20% false positive rate, so there are several ways to rate your algorithms.
The test data should attempt to be designed to cover as many types of dynamics as possible that you would exp...
String concatenation in Ruby
...ficient in term of memory/speed from what I've seen (not measured though). All three methods will throw an uninitialized constant error when ROOT_DIR is nil.
When dealing with pathnames, you may want to use File.join to avoid messing up with pathname separator.
In the end, it is a matter of taste....
Join/Where with LINQ and Lambda
...re post.ID == id
select new { Post = post, Meta = meta };
If you're really stuck on using lambdas though, your syntax is quite a bit off. Here's the same query, using the LINQ extension methods:
var id = 1;
var query = database.Posts // your starting point - table in the "from" statement
...
When to use Amazon Cloudfront or S3
...When end users request an object using this domain name, they are automatically routed to the nearest edge location for high performance delivery of your content. (Amazon)
The data served by CloudFront may or may not come from S3. Since it is more optimized for delivery speed, the bandwidth costs ...
How to define an enumerated type (enum) in C?
...ollowing works without any complaints (compiled with gcc -ansi -pedantic -Wall):
#include <stdio.h>
enum { RANDOM, IMMEDIATE, SEARCH } strategy = IMMEDIATE;
int main(int argc, char** argv){
printf("strategy: %d\n", strategy);
return 0;
}
If instead of the above, the second line wer...
How do I delete unpushed git commits?
I accidentally committed to the wrong branch.
How do I delete that commit?
7 Answers
7...