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Pure virtual destructor in C++
... {
public:
virtual ~A() = 0;
};
inline A::~A() { }
should suffice.
And since this got a down vote, I should clarify: If you derive anything from A and then try to delete or destroy it, A's destructor will eventually be called. Since it is pure and doesn't have an implementation, undefined be...
PHP session lost after redirect
...nt script using exit(); (Others have also suggested session_write_close(); and session_regenerate_id(true), you can try those as well, but I'd use exit();)
Make sure cookies are enabled in the browser you are using to test it on.
Ensure register_globals is off, you can check this on the php.ini file...
What's the difference between isset() and array_key_exists()? [duplicate]
...n an array, whereas isset will only return true if the key/variable exists and is not null.
$a = array('key1' => 'フーバー', 'key2' => null);
isset($a['key1']); // true
array_key_exists('key1', $a); // true
isset($a['key2']); // false
array_key_exists('key2', $a...
Why doesn't nodelist have forEach?
... why NodeList doesn't inherit from Array, thus allowing it to have forEach and all the rest.
The answer is found on this es-discuss thread. In short, it breaks the web:
The problem was code that incorrectly assumed instanceof to mean that the instance was an Array in combination with Array.prototyp...
Get the current URL with JavaScript?
...age loading I need to be able to grab the full, current URL of the website and set it as a variable to do with as I please.
...
Bash variable scope
...he while loop.
Now this child process has its own copy of the environment and can't pass any
variables back to its parent (as in any unix process).
Therefore you'll need to restructure so that you're not piping into the loop.
Alternatively you could run in a function, for example, and echo the val...
Naming Classes - How to avoid calling everything a “Manager”? [closed]
... but where possible I try to copy the names already in the .NET framework, and I look for ideas in the Java and Android frameworks.
It seems Helper, Manager, and Util are the unavoidable nouns you attach for coordinating classes that contain no state and are generally procedural and static. An alte...
avoid page break inside row of table
...of tr as block or some thing else then it change the formatting of table and insert double border.
Or it is possible to insert the table header on each page, where the table was splitted.
...
Django: Get an object form the DB, or 'None' if nothing matches
...orks exactly as it suppose to. It returns the first object in query result and doesn't cares if multiple results are found. If you need to check for multiple objects returned you should use .get() instead.
– Cesar Canassa
Mar 13 '14 at 15:03
...
MySQL/SQL: Group by date only on a Datetime column
...able GROUP BY DATE(a_table.mydate);
Or you can GROUP BY the alias as @orlandu63 suggested:
SELECT SUM(foo), DATE(mydate) DateOnly FROM a_table GROUP BY DateOnly;
Though I don't think it'll make any difference to performance, it is a little clearer.
...