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What is the difference between declarative and imperative programming? [closed]
I have been searching the web looking for a definition for declarative and imperative programming that would shed some light for me. However, the language used at some of the resources that I have found is daunting - for instance at Wikipedia .
Does anyone have a real-world example that they could ...
Why doesn't Dijkstra's algorithm work for negative weight edges?
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Recall that in Dijkstra's algorithm, once a vertex is marked as "closed" (and out of the open set) - the algorithm found the shortest path to it, and will never have to develop this node again - it assumes the path developed to this path is the shortest.
But with negative weights - it might not be...
In Python, when to use a Dictionary, List or Set?
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A list keeps order, dict and set don't: when you care about order, therefore, you must use list (if your choice of containers is limited to these three, of course;-).
dict associates with each key a value, while list and set just contain values: ver...
Which encoding opens CSV files correctly with Excel on both Mac and Windows?
...s CSV files containing foreign characters with UTF-8, no BOM. Both Windows and Mac users get garbage characters in Excel. I tried converting to UTF-8 with BOM; Excel/Win is fine with it, Excel/Mac shows gibberish. I'm using Excel 2003/Win, Excel 2011/Mac.
Here's all the encodings I tried:
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Array.Copy vs Buffer.BlockCopy
Array.Copy and Buffer.BlockCopy both do the same thing, but BlockCopy is aimed at fast byte-level primitive array copying, whereas Copy is the general-purpose implementation. My question is - under what circumstances should you use BlockCopy ? Should you use it at any time when you are copyi...
Should I implement __ne__ in terms of __eq__ in Python?
...legate to __ne__ on the other side, not self == other is (assuming the operand's __eq__ doesn't know how to compare the other operand) implicitly delegating to __eq__ from the other side, then inverting it. For weird types, e.g. the SQLAlchemy ORM's fields, this causes problems.
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Equivalent of LIMIT and OFFSET for SQL Server?
In PostgreSQL there is the Limit and Offset keywords which will allow very easy pagination of result sets.
16 Answers
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Best way to test for a variable's existence in PHP; isset() is clearly broken
...l scope variables as well, on can do a $defined_vars = get_defined_vars(); and then test via array_key_exists('v', $defined_vars);.
– Henrik Opel
Sep 27 '10 at 16:01
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Why is SSE scalar sqrt(x) slower than rsqrt(x) * x?
I've been profiling some of our core math on an Intel Core Duo, and while looking at various approaches to square root I've noticed something odd: using the SSE scalar operations, it is faster to take a reciprocal square root and multiply it to get the sqrt, than it is to use the native sqrt opcode!...
When should we use intern method of String on String literals
...in String pool, otherwise a new string object will be added in String pool and the reference of this String is returned.
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