大约有 30,000 项符合查询结果（耗时：0.0230秒） [XML]
What's the fastest way to merge/join data.frames in R?
...r R session constitute the data base, not the tables in sqlite. Thus each time the code refers to an unqualified table name it will look in your R workspace for it -- not in sqlite's main database. Thus the select statement that was shown reads d1 and d2 from the workspace into sqlite's main datab...
How does Stack Overflow generate its SEO-friendly URLs?
... I figured I'd optimize it because this function can be called hundreds of times per page.
/// <summary>
/// Produces optional, URL-friendly version of a title, "like-this-one".
/// hand-tuned for speed, reflects performance refactoring contributed
/// by John Gietzen (user otac0n)
/// <...
Printing without newline (print 'a',) prints a space, how to remove?
... @katrielalex Wrong, string concatenation using += in Python is a constant time operation for concatenation of a single character.
– moinudin
Dec 21 '10 at 13:06
...
C/C++ line number
... all C++ compilers support it)
__DATE__ : a string of form "Mmm dd yyyy"
__TIME__ : a string of form "hh:mm:ss"
Your code will be :
if(!Logical)
printf("Not logical value at line number %d in file %s\n", __LINE__, __FILE__);
...
Passing properties by reference in C#
...tually IL compiled code and therefore using constant number of accessors n-times would be okay, but using total of n accessors (high ctor cost) would not.
– mancze
Sep 15 '17 at 8:16
...
What does T&& (double ampersand) mean in C++11?
...gled to understand why people do a T &&t; std::move(t); for a long time in move ctors, and the like.
– legends2k
May 30 '13 at 12:32
...
How do I convert a TimeSpan to a formatted string? [duplicate]
I have two DateTime vars, beginTime and endTime. I have gotten the difference of them by doing the following:
14 Answers
...
Print a file's last modified date in Bash
...
You can use the
stat
command
stat -c %y "$entry"
More info
%y time of last modification, human-readable
share
|
improve this answer
|
follow
|
...
Remove the first character of a string
...e title and the body of the question.. In hindsight, should have spent the time getting coffee. :-)
– Spaceghost
Feb 9 '11 at 14:36
add a comment
|
...
What is the best way to ensure only one instance of a Bash script is running? [duplicate]
...ready running
flock -n /var/lock/myjob.lock my_bash_command
Use -w for timeouts or leave out options to wait until the lock is released. Finally, the man page shows a nice example for multiple commands:
(
flock -n 9 || exit 1
# ... commands executed under lock ...
) 9>/var/l...