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Using group by on multiple columns
I understand the point of GROUP BY x .
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Why do we need a pure virtual destructor in C++?
I understand the need for a virtual destructor. But why do we need a pure virtual destructor? In one of the C++ articles, the author has mentioned that we use pure virtual destructor when we want to make a class abstract.
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Cmake vs make sample codes?
I was wondering if there was any sample code for Makefile s ( make ) and CMakeLists.txt ( cmake ) that both do the same thing (the only difference being that one is written in make and the other in cmake ).
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What is the difference between Set and List?
What is the fundamental difference between the Set<E> and List<E> interfaces?
27 Answers
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How do you implement a Stack and a Queue in JavaScript?
What is the best way to implement a Stack and a Queue in JavaScript?
24 Answers
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C++ Tuple vs Struct
Is there is any difference between using a std::tuple and a data-only struct ?
12 Answers
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In what situations would AJAX long/short polling be preferred over HTML5 WebSockets?
...sends request headers with optional data, gets a response from the server, and closes the connection.
Supported in all major browsers.
Long poll - request → wait → response. Creates a connection to the server like AJAX does, but maintains a keep-alive connection open for some time (not long tho...
Python dictionary from an object's fields
...class Foo(object):
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Also, there's a difference between an 'object' and a 'class'. To build a dictionary from an arbitrary object, it's sufficient to use __dict__. Usually, you'll declare your methods at class level and your attributes at instance level, so __dict__ should be fine. For exampl...
MySQL error: key specification without a key length
...r BLOB types such as TINYBLOB, MEDIUMBLOB, LONGBLOB, TINYTEXT, MEDIUMTEXT, and LONGTEXT that you try to make a primary key or index. With full BLOB or TEXT without the length value, MySQL is unable to guarantee the uniqueness of the column as it’s of variable and dynamic size. So, when using BLOB ...
Including all the jars in a directory within the Java classpath
...ion. See also: Execute jar file with multiple classpath libraries from command prompt)
Understanding Wildcards
From the Classpath document:
Class path entries can contain the basename wildcard character *, which is considered equivalent to specifying a list of all the files
in the directory with th...