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Python using enumerate inside list comprehension
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Just to be really clear, this has nothing to do with enumerate and everything to do with list comprehension syntax.
This list comprehension returns a list of tuples:
[(i,j) for i in range(3) for j in 'abc']
this a list of dicts:
[{i:...
A std::map that keep track of the order of insertion?
...::sort using appropriate functor.
Or you could use boost::multi_index. It allows to use several indexes.
In your case it could look like the following:
struct value_t {
string s;
int i;
};
struct string_tag {};
typedef multi_index_container<
value_t,
indexed_by<
...
How to count occurrences of a column value efficiently in SQL?
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If you're using Oracle, then a feature called analytics will do the trick. It looks like this:
select id, age, count(*) over (partition by age) from students;
If you aren't using Oracle, then you'll need to join back to the counts:
select a.id, a.age, b.age_co...
How to compare two dates?
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@Emadpres: imagine this was typed manually. The past line was typed first, while the present line was typed second... so the past line was entered first, so past < present is True.
– ramcdougal
Mar 20 '17 at 15:50
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Why is argc not a constant?
...ting C code was an early goal of C++.
Some UNIX APIs, such as getopt, actually do manipulate argv[], so it can't be made const for that reason also.
(Aside: Interestingly, although getopt's prototype suggests it won't modify argv[] but may modify the strings pointed to, the Linux man page indica...
Swapping column values in MySQL
...test s1, swap_test s2 SET s1.x=s1.y, s1.y=s2.x WHERE s1.id=s2.id;
Essentially, the 1st table is the one getting updated and the 2nd one is used to pull the old data from.
Note that this approach requires a primary key to be present.
This is my test schema:
CREATE TABLE `swap_test` (
`id` int(1...
Cross-browser multi-line text overflow with ellipsis appended within a fixed width and height
...cess remains invisible and even with JS turned off the result remains 'visually correct' (without the "..." of course).
If you combine this with a sensible truncation on the server-side (that leaves only a small overhead) then it will run quicker :).
Again, this is not a complete solution, just an...
Django in / not in query
...e(); Tbl2.objects.filter(id__in=IDs') This did not work because IDs is actually a QuerySet object. When I deleted the rows it originated from, it no longer worked with other queries. The solution is Tbl2.objects.filter(id__in=list(IDs)) -- turn it into a list
– Dakusan
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What is difference between cacerts and keystore?
...he keystore. (Confusingly, the same file format is used for both and it's called a keystore file.)
– Marquis of Lorne
Jul 29 '13 at 23:44
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Test if a class has an attribute?
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to only check if the attribute is present, which is usually all that is needed for parameterless/propertyless attributes, it's cheaper to use .IsDefined, as it will query the metadata, and not deserialize and instantiate the attribute object.
– Lasse V. Karl...