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How to Sort a List by a property in the object
I have a class called Order which has properties such as OrderId , OrderDate , Quantity , and Total . I have a list of this Order class:
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how to emulate “insert ignore” and “on duplicate key update” (sql merge) with postgresql?
...gsql-control-structures.html, example 40-2 right at the bottom.
That's usually the easiest way. You can do some magic with rules, but it's likely going to be a lot messier. I'd recommend the wrap-in-function approach over that any day.
This works for single row, or few row, values. If you're deali...
What is the difference between const int*, const int * const, and int const *?
...= int const *
const int * const == int const * const
If you want to go really crazy you can do things like this:
int ** - pointer to pointer to int
int ** const - a const pointer to a pointer to an int
int * const * - a pointer to a const pointer to an int
int const ** - a pointer to a pointer t...
Inheriting constructors
...explicit A(int x) {}
};
class B: public A
{
using A::A;
};
This is all or nothing - you cannot inherit only some constructors, if you write this, you inherit all of them. To inherit only selected ones you need to write the individual constructors manually and call the base constructor as nee...
In Scala, what exactly does 'val a: A = _' (underscore) mean?
....0d if T is Double,
false if T is Boolean,
() if T is Unit,
null for all other types T.
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Split a vector into chunks in R
...ks of size 20:
split(d, ceiling(seq_along(d)/20))
More details: I think all you need is seq_along(), split() and ceiling():
> d <- rpois(73,5)
> d
[1] 3 1 11 4 1 2 3 2 4 10 10 2 7 4 6 6 2 1 1 2 3 8 3 10 7 4
[27] 3 4 4 1 1 7 2 4 6 0 5 7 4 6 8 4 7 1...
How do I tell Matplotlib to create a second (new) plot, then later plot on the old one?
I want to plot data, then create a new figure and plot data2, and finally come back to the original plot and plot data3, kinda like this:
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JavaScript by reference vs. by value [duplicate]
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My understanding is that this is actually very simple:
Javascript is always pass by value, but when a variable refers to an object (including arrays), the "value" is a reference to the object.
Changing the value of a variable never changes the underlying prim...
How can I search for a multiline pattern in a file?
I needed to find all the files that contained a specific string pattern. The first solution that comes to mind is using find piped with xargs grep :
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What are bitwise operators?
I'm someone who writes code just for fun and haven't really delved into it in either an academic or professional setting, so stuff like these bitwise operators really escapes me.
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