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What is the result of % in Python?
...ch out if you are coming from a language with automatic type casting (like PHP or JS) where an expression like '12' % 2 + 3 is legal: in Python it will result in TypeError: not all arguments converted during string formatting which probably will be pretty confusing for you.
[update for Python 3]
Use...
Subtract two variables in Bash
...a whitespace around the minus sign, and backticks:
COUNT=`expr $FIRSTV - $SECONDV`
Be aware of the exit status:
The exit status is 0 if EXPRESSION is neither null nor 0, 1 if EXPRESSION is null or 0.
Keep this in mind when using the expression in a bash script in combination with set -e which w...
How to delete duplicates on a MySQL table?
...:22:22 |
+------+----------+---------------------+
6 rows in set (0.00 sec)
Remove the duplicates in place:
delete a
from penguins a
left join(
select max(baz) maxtimestamp, foo, bar
from penguins
group by foo, bar) b
on a.baz = maxtimestamp and
a.foo = b.foo and
...
What does the Reflect object do in JavaScript?
...by the draft document found on the wiki,
http://wiki.ecmascript.org/doku.php?id=harmony:specification_drafts
We get the line about "single ordinary object" which it clarifies in the draft. It also has the function definitions.
The wiki should be reliable since you can find a link to it from the ...
MySQL error: key specification without a key length
...uest, something like:
alter table authors ADD UNIQUE(name_first(20), name_second(20));
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How can I generate Unix timestamps?
...
In Linux or MacOS you can use:
date +%s
where
+%s, seconds since 1970-01-01 00:00:00 UTC. (GNU Coreutils 8.24 Date manual)
Example output now 1454000043.
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Alarm Manager Example
...nager.RTC_WAKEUP, System.currentTimeMillis(), 1000 * 60 * 10, pi); // Millisec * Second * Minute
}
public void cancelAlarm(Context context)
{
Intent intent = new Intent(context, Alarm.class);
PendingIntent sender = PendingIntent.getBroadcast(context, 0, intent, 0);
...
How to retrieve the current version of a MySQL database management system (DBMS)?
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5 rows in set (0.04 sec)
MySQL 5.0 Reference Manual (pdf) - Determining Your Current MySQL Version - page 42
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How to use QueryPerformanceCounter?
I recently decided that I needed to change from using milliseconds to microseconds for my Timer class, and after some research I've decided that QueryPerformanceCounter is probably my safest bet. (The warning on Boost::Posix that it may not works on Win32 API put me off a bit). However, I'm not re...
Difference between two dates in MySQL
... two dates, in the format YYYY-MM-DD hh: mm: ss and to get the result in seconds or milliseconds?
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