大约有 47,000 项符合查询结果（耗时：0.0564秒） [XML]
What is the difference between a var and val definition in Scala?
...a number out of them. For example, if I have a queue with 2, 1, 3, in that order, I want to get back the number 213. Let's first solve it with a mutable.Queue:
def toNum(q: scala.collection.mutable.Queue[Int]) = {
var num = 0
while (!q.isEmpty) {
num *= 10
num += q.dequeue
}
num
}
...
How do I force Postgres to use a particular index?
...
I even had to set random_page_cost = 0.1 in order to make index scan work on large (~600M rows table) in Pg 10.1 on Ubuntu. Without the tweak, seq scan (despite being parallel) was taking 12 mins (Note that Analyze table was performed!). Drive is SSD. After the tweak,...
What is the preferred syntax for defining enums in JavaScript?
... some assumptions can no longer be made (that value represents the correct order for the size for example).
Remember, in JavaScript an object is just like a map or hash table. A set of name-value pairs. You can loop through them or otherwise manipulate them without knowing much about them in advan...
How to get CRON to call in the correct PATHs
...
I used /etc/crontab. I used vi and entered in the PATHs I needed into this file and ran it as root. The normal crontab overwrites PATHs that you have set up. A good tutorial on how to do this.
The systemwide cron file looks like thi...
What's faster, SELECT DISTINCT or GROUP BY in MySQL?
...he output, and GROUP BY by default does. However, in MySQL even a DISTINCT+ORDER BY might still be faster than a GROUP BY due to the extra hints for the optimizer as explained by SquareCog.
– rustyx
Jan 25 '15 at 15:03
...
.NET XML serialization gotchas? [closed]
...L through a web page (ASP.NET), you don't want to include the Unicode Byte-Order Mark. Of course, the ways to use or not use the BOM are almost the same:
BAD (includes BOM):
XmlTextWriter wr = new XmlTextWriter(stream, new System.Text.Encoding.UTF8);
GOOD:
XmlTextWriter wr = new XmlTextWriter(...
Efficiently convert rows to columns in sql server
... yourtable
group by ColumnName, id
order by id
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set @query = N'SELECT ' + @cols + N' from
(
select value, ColumnName
fr...
How to make a SIMPLE C++ Makefile
...hat is, it takes care of knowing what commands need to be executed in what order to take your software project from a collection of source files, object files, libraries, headers, etc., etc.---some of which may have changed recently---and turning them into a correct up-to-date version of the program...
Relative imports in Python 2.7
...ia sys.path . Additional code that manipulates sys.path would be needed in order for direct execution to work without the top level package already being importable." -- this is the most disturbing bit to me since this "additional code" is actually quite long and can't be stored elsewhere in package...
How to detect DIV's dimension changed?
... slow as hell. A requestAnimationFrame that checks for a simple boolean is orders of magnitude faster than a setTimeout checking all the time against DOM properties. Beside that setTimeout is also called every few milliseconds.
– Marc J. Schmidt
Mar 17 '16 at 1...