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C++ lambda with captures as a function pointer
...fn;
}
};
Exapmle
int a = 100;
auto b = [&](void*) {return ++a;};
Converting lambda with captures to a C pointer
void (*f1)(void*) = Lambda::ptr(b);
f1(nullptr);
printf("%d\n", a); // 101
Can be used this way as well
auto f2 = Lambda::ptr(b);
f2(nullptr);
printf("%d\n", a); // 102
In ca...
What's the best way to get the last element of an array without deleting it?
...st a day, so if I need to do it again I will probably write something that converts the output of all 210 docker executions to a table automatically :-)
– Paul van Leeuwen
Sep 29 '18 at 20:07
...
How do I (or can I) SELECT DISTINCT on multiple columns?
...
SELECT DISTINCT a,b,c FROM t
is roughly equivalent to:
SELECT a,b,c FROM t GROUP BY a,b,c
It's a good idea to get used to the GROUP BY syntax, as it's more powerful.
For your query, I'd do it like this:
UPDATE sale...
SELECT * WHERE NOT EXISTS
...uming these tables should be joined on employeeID, use the following:
SELECT *
FROM employees e
WHERE NOT EXISTS
(
SELECT null
FROM eotm_dyn d
WHERE d.employeeID = e.id
)
You can join these tables with a LEFT JOIN keyword and filter out the...
Is there a C# case insensitive equals operator?
...ore case string comparison. This is also the fastest way, much faster than converting the strings to lower or upper case and comparing them after that.
I tested the performance of both approaches and the ordinal ignore case string comparison was more than 9 times faster! It is also more reliable th...
Ruby capitalize every word first letter
...as"
"kirkDouglas"
"KirkDouglas"
#titleize gotchas
Rails's titleize will convert things like dashes and underscores into spaces and can produce other unexpected results, especially with case-sensitive situations as pointed out by @JamesMcMahon:
"hEy lOok".titleize #=> "H Ey Lo Ok"
because it...
How to set variables in HIVE scripts
...riable substitution.
e.g.
hive> set CURRENT_DATE='2012-09-16';
hive> select * from foo where day >= ${hiveconf:CURRENT_DATE}
similarly, you could pass on command line:
% hive -hiveconf CURRENT_DATE='2012-09-16' -f test.hql
Note that there are env and system variables as well, so you can r...
Calculate a Running Total in SQL Server
... somewhat limited.
Oracle (and ANSI-SQL) allow you to do things like:
SELECT somedate, somevalue,
SUM(somevalue) OVER(ORDER BY somedate
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)
AS RunningTotal
FROM Table
SQL Server gives you no clean solution to this problem. My ...
Bash syntax error: unexpected end of file
...m on StackOverflow
Open the file in Vim and try
:set fileformat=unix
Convert eh line endings to unix endings and see if that solves the
issue. If editing in Vim, enter the command :set fileformat=unix and
save the file. Several other editors have the ability to convert line
endings, such...
MySQL “Group By” and “Order By”
I want to be able to select a bunch of rows from a table of e-mails and group them by the from sender. My query looks like this:
...