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How can I format a nullable DateTime with ToString()?
How can I convert the nullable DateTime dt2 to a formatted string?
20 Answers
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Hidden features of C
...
Function pointers. You can use a table of function pointers to implement, e.g., fast indirect-threaded code interpreters (FORTH) or byte-code dispatchers, or to simulate OO-like virtual methods.
Then there are hidden gems in the stand...
Non-static variable cannot be referenced from a static context
...ecific instance. For methods, this usually are global helper methods (like Integer.parseInt()). For fields, it's usually constants (like car types, i.e. something where you have a limited set which doesn't change often).
To solve your problem, you need to instantiate an instance (create an object) ...
Format Instant to String
...-zone is required. Without a time-zone, the formatter does not know how to convert the instant to human date-time fields, and therefore throws an exception.
The time-zone can be added directly to the formatter using withZone().
DateTimeFormatter formatter =
DateTimeFormatter.ofLocalizedDateTim...
How can I pass a list as a command-line argument with argparse?
... 'append' setting of the action option (depending on how you want the user interface to behave).
nargs
parser.add_argument('-l','--list', nargs='+', help='<Required> Set flag', required=True)
# Use like:
# python arg.py -l 1234 2345 3456 4567
nargs='+' takes 1 or more arguments, nargs='*' ...
Which is better, return value or out parameter?
...else, it stops the caller from having to declare the variable separately:
int foo;
GetValue(out foo);
vs
int foo = GetValue();
Out values also prevent method chaining like this:
Console.WriteLine(GetValue().ToString("g"));
(Indeed, that's one of the problems with property setters as well, a...
Read environment variables in Node.js
... but don't forget that assigning a property on process.env will implicitly convert the value to a string.
Avoid Boolean Logic
Even if your .env file defines a variable like SHOULD_SEND=false or SHOULD_SEND=0, the values will be converted to strings (“false” and “0” respectively) and not...
Getting the current page
...no UIScrollView property for the current page. You can calculate it with:
int page = scrollView.contentOffset.x / scrollView.frame.size.width;
If you want to round up or down to the nearest page, use:
CGFloat width = scrollView.frame.size.width;
NSInteger page = (scrollView.contentOffset.x + (0....
Calculate a Running Total in SQL Server
...ee: MAXDOP):
Full working sample:
drop table #t
create table #t ( ord int primary key, total int, running_total int)
insert #t(ord,total) values (2,20)
-- notice the malicious re-ordering
insert #t(ord,total) values (1,10)
insert #t(ord,total) values (3,10)
insert #t(ord,total) values (4,1...
Structure padding and packing
...
Padding aligns structure members to "natural" address boundaries - say, int members would have offsets, which are mod(4) == 0 on 32-bit platform. Padding is on by default. It inserts the following "gaps" into your first structure:
struct mystruct_A {
char a;
char gap_0[3]; /* inserted by...