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MySQL combine two columns into one column
...f the values to numbers. If a value does not start with a digit, then the converted value is 0.
So try this:
select concat(column1, column2)
Two ways to add a space:
select concat(column1, ' ', column2)
select concat_ws(' ', column1, column2)
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How does collections.defaultdict work?
...re precisely, it's an arbitrary "callable" object, which includes function and type objects). For the first example, default items are created using int(), which will return the integer object 0. For the second example, default items are created using list(), which returns a new empty list object....
What does InitializeComponent() do, and how does it work in WPF?
...dComponent() loads the XAML file that is located at the passed in URI, and converts it to an instance of the object that is specified by the root element of the XAML file.
In more detail, LoadComponent creates an instance of the XamlParser, and builds a tree of the XAML. Each node is parsed by the ...
Find unique rows in numpy.array
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To avoid a FutureWarning, convert the set to a list like: np.vstack(list({tuple(row) for row in AIPbiased[i, :, :]})) FutureWarning: arrays to stack must be passed as a "sequence" type such as list or tuple. Support for non-sequence iterables such as...
What is the difference between an int and a long in C++?
... (an answer by example) with some of the details below regarding the C++ standard. The draft for C++0x is at open-std.org/JTC1/SC22/WG21/docs/papers/2008/n2798.pdf and it is marked up so you can see the differences between it and the last rev.
– Patrick Johnmeyer
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How to pass optional arguments to a method in C++?
... else
do_something_else();
}
you can call myfunc in both ways and both are valid
myfunc(10); // Mode will be set to default 0
myfunc(10, 1); // Mode will be set to 1
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Performance of Arrays vs. Lists
...u need to have a list/array of integers which you need iterate frequently, and I mean extremely often. The reasons may vary, but say it's in the heart of the inner most loop of a high volume processing.
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Is it possible to print a variable's type in standard C++?
... update to a very old question: Print variable type in C++.
The accepted (and good) answer is to use typeid(a).name(), where a is a variable name.
Now in C++11 we have decltype(x), which can turn an expression into a type. And decltype() comes with its own set of very interesting rules. For exam...
Can I call a base class's virtual function if I'm overriding it?
Say I have classes Foo and Bar set up like this:
7 Answers
7
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Why use double indirection? or Why use pointers to pointers?
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Yes, and if you ever lose track of one of your pointers, here's a pointer: pointerpointer.com
– Andrew Cheong
Aug 21 at 0:50
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