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【BLE技术内幕】BLE技术揭秘 - 创客硬件开发 - 清泛IT论坛，有思想、有深度
...用send_LL(0x53,2402M)（注：2402M为信道频率）。这里还有一个问题，设备B怎么知道这个数据包是发给自己的还是其他人的，为此BLE引入access address概念，用来指明接收者身份，其中，0x8E89BED6这个access address比较特殊，它表示要发给周...
PHP-FPM doesn't write to error log
I've just installed a nginx+php-fpm server. Everything seems fine except that PHP-FPM never writes error to its log.
11 Ans...
what is faster: in_array or isset? [closed]
... value until it finds a match.
Being an opcode, it has less overhead than calling the in_array built-in function.
These can be demonstrated by using an array with values (10,000 in the test below), forcing in_array to do more searching.
isset: 0.009623
in_array: 1.738441
This builds on Jason...
Remove all files except some from a directory
When using sudo rm -r , how can I delete all files, with the exception of the following:
19 Answers
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MySQL OPTIMIZE all tables?
...ZE TABLE command which can be used to reclaim unused space in a MySQL install. Is there a way (built-in command or common stored procedure) to run this optimization for every table in the database and/or server install, or is this something you'd have to script up yourself?
...
Where can I find php.ini?
A few years ago I installed Apache 2.2x and PHP 5.3.1 on a Linux server I maintain. I used .tar.gz's and built them as instructed (instead of rpms and what-have-you). And all was fine.
...
What's better to use in PHP, $array[] = $value or array_push($array, $value)?
...
No benchmarks, but I personally feel like $array[] is cleaner to look at, and honestly splitting hairs over milliseconds is pretty irrelevant unless you plan on appending hundreds of thousands of strings to your array.
Edit: Ran this code:
$t = microti...
Multi-line strings in PHP
...ng
spanning multiple lines
using heredoc syntax.
$var is replaced automatically.
EOD;
A Nowdoc is like a Heredoc, but it doesn't replace variables.
$str = <<<'EOD'
Example of string
spanning multiple lines
using nowdoc syntax.
$var is NOT replaced in a nowdoc.
EOD;
Beware that the end ...
Using a .php file to generate a MySQL dump
... can be done by the command itself.
That external command will :
be a call to mysqldump, with the right parameters,
and redirect the output to a file.
For example :
mysqldump --user=... --password=... --host=... DB_NAME > /path/to/output/file.sql
Which means your PHP code would look li...
How can I count all the lines of code in a directory recursively?
We've got a PHP application and want to count all the lines of code under a specific directory and its subdirectories. We don't need to ignore comments, as we're just trying to get a rough idea.
...