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Python: fastest way to create a list of n lists
...
The probably only way which is marginally faster than
d = [[] for x in xrange(n)]
is
from itertools import repeat
d = [[] for i in repeat(None, n)]
It does not have to create a new int object in every iteration and is about 15 % faster on my machine.
Edi...
Why is string concatenation faster than array join?
...ring concatenation. Beginning with version 1.0, the array technique is actually slower than using the plus operator in all cases. Other browsers have also optimized string concatenation, so Safari, Opera, Chrome, and Internet Explorer 8 also show better performance using the plus operator. Internet ...
How to properly add cross-site request forgery (CSRF) token using PHP
... deterministically
Try this out:
Generating a CSRF Token
PHP 7
session_start();
if (empty($_SESSION['token'])) {
$_SESSION['token'] = bin2hex(random_bytes(32));
}
$token = $_SESSION['token'];
Sidenote: One of my employer's open source projects is an initiative to backport random_bytes() a...
List the queries running on SQL Server
...
You can run the sp_who command to get a list of all the current users, sessions and processes. You can then run the KILL command on any spid that is blocking others.
share
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get the latest fragment in backstack
...gment in the back stack twice, you can't retrieve a specific fragment when all you have is the index or backstackentry entity.
– Justin
May 29 '14 at 15:54
14
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How to keep environment variables when using sudo
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To allow -E (preserve environment) for wget, you need to specify the SETENV tag on the sudo rule that allows the running of wget -- Example: <username> ALL=(root) NOPASSWD:SETENV: <path to wget>
...
What is the easiest way to remove the first character from a string?
... only does one and finishes. Consider gsub like it's a minimum of two sub calls.
Also, it's important to remember that gsub, and sub can also be handicapped by poorly written regex which match much more slowly than a sub-string search. If possible anchor the regex to get the most speed from it. Th...
房多多：懂用户比懂互联网重要 - 资讯 - 清泛网 - 专注C/C++及内核技术
...以提高售房效率。
移动互联时代，人手一部智能手机，App成了对话的窗口，房地产销售有了新场景。以售楼处和中介门店为核心的销售模式弊端显现。
这种情况也曾经在贸易行业存在过，但都被阿里巴巴改造了。所以我决定...
Swift compiler segmentation fault when building
...Thanks, this is my case too. Swift has been giving me unpleasant surprises all along the way, but this one is way over the limit.
– CodeBrew
Feb 15 '15 at 22:37
...
Why should I prefer to use member initialization lists?
...tyle. For class members which are classes, then it avoids an unnecessary call to a default constructor. Consider:
class A
{
public:
A() { x = 0; }
A(int x_) { x = x_; }
int x;
};
class B
{
public:
B()
{
a.x = 3;
}
private:
A a;
};
In this case, the construct...