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Why does InetAddress.isReachable return false, when I can ping the IP address?
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// in case of Linux change the 'n' to 'c'
Process p1 = java.lang.Runtime.getRuntime().exec("ping -n 1 www.google.com");
int returnVal = p1.waitFor();
boolean reachable = (returnVal==0);
The -c option of ping will allow ping to simply try to reach the server once(as opposed to the in...
Why does i = i + i give me 0?
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This is my favorite answer on this site ever of all times.
– Lee White
Jun 12 '14 at 14:24
2
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Haskell: Lists, Arrays, Vectors, Sequences
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The first problem with lists is that to index into them (!!) takes ϴ(k) time, which is annoying. Also, appends can be slow ++, but Haskell's lazy evaluation model means that these can be treated as fully amortized, if they happen at all.
The second problem with lists is that they have poor data ...
Iterate over object attributes in python
... can lead to problems if you're not careful, so the above method might sometimes be better (though copying the dictionary is probably easier). Also, note that while the dictionary returned above isn't the instance's __dict__, the values are the same, so modifying any mutable values will still be ref...
PHP abstract properties
..., there is no way to enforce that with the compiler, you'd have to use run-time checks (say, in the constructor) for the $tablename variable, e.g.:
class Foo_Abstract {
public final function __construct(/*whatever*/) {
if(!isset($this->tablename))
throw new LogicException(get_class($...
What does “SyntaxError: Missing parentheses in call to 'print'” mean in Python?
...o!")?
Since the "Missing parentheses in call to print" case is a compile time syntax error and hence has access to the raw source code, it's able to include the full text on the rest of the line in the suggested replacement. However, it doesn't currently try to work out the appropriate quotes to p...
Do sessions really violate RESTfulness?
...ate of this key must be maintained and it has some sort of expiration date/time after which it no longer grants access. However, as I mentioned at the top of my post, sacrifices must be made to allow an application to actually work. That said, authentication tokens must be stored in a way that all...
What are copy elision and return value optimization?
... to a temp, and copy 2 from temp to obj; 2nd is when one of the above is optimezed, probably the reutnr copy is elided; the thris both are elided
– victor
Nov 7 '14 at 16:06
3
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Replace specific characters within strings
...g regular expressions, which allow more flexible pattern matching but take time to compute. If all that's needed is removing a single constant string "e", they aren't necessary.
– mm689
Oct 31 '16 at 19:16
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Finding local IP addresses using Python's stdlib
How can I find local IP addresses (i.e. 192.168.x.x or 10.0.x.x) in Python platform independently and using only the standard library?
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