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问题需要满足以下几个特性

  1. 存在一种模式或者说一种表现可以让我们对它进行改造提高
  2. 规则并不容易定义
  3. 需要有数据

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关于Luhn算法

参考：

https://en.wikipedia.org/wiki/Luhn_algorithm

https://baike.baidu.com/item/Luhn算法

PHP代码实现

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class Luhn
{
    /**
     * 补填校验位
     * @param string $rawNo 原始号码
     * @return string 补填校验位后的号码
     */
    public static function gen($rawNo)
    {
        return $rawNo . self::calcCheckNum($rawNo);
    }

    /**
     * 校验给定数据
     * @param string $no 需要校验的数据
     * @return bool true:通过|false:不通过
     */
    public static function verify($no)
    {
        $rawNo   = substr($no, 0, -1);
        $checkNo = intval(substr($no, -1));
        return $checkNo == self::calcCheckNum($rawNo);
    }

    /**
     * 计算校验值
     * @param string $rawStr 原始字符串(不含校验位)
     * @return int 校验值
     */
    private static function calcCheckNum($rawStr)
    {
        $strrev = strrev($rawStr);
        $sum    = 0;
        for ($i = 0; $i < strlen($strrev); $i++) {
            $val = intval($strrev[$i]);
            $sum += ($i % 2 == 0) ? ($val > 4 ? (2 * $val - 9) : (2 * $val)) : $val;
        }
        $ret = 10 - $sum % 10;
        return $ret == 10 ? 0 : $ret;
    }
}

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1. Vagrantfile

下面为1个master和3个node的配置

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# 启动Node的数量
$workerNodeNumber = 3

# IP前缀
$workerNodeIpBase = "192.168.33."

# Node的IP地址数组(从192.168.33.20开始分配)
$workerNodeIps = $workerNodeNumber.times.collect {|n| $workerNodeIpBase + "#{n+20}"}

Vagrant.configure("2") do |config|

  # 定义master
  config.vm.define "master" do |master|
    master.vm.box = "centos7" # centos7为本地的box(使用`vagrant box list`查看)
    master.vm.network "private_network", ip: $workerNodeIpBase + "10" # 192.168.33.10
    master.vm.hostname = "master"
    master.vm.provider "virtualbox" do |vb|
      vb.memory = "1024" # 定义master机器的内存：1024MB
      vb.cpus = "1" # 定义master机器的CPU数量：1
      vb.name = "master" # 虚拟机名称(在VirtualBox中显示)
    end
  end

  # 定义node
  $workerNodeNumber.times do |n|
    vmName = "node#{n}"
    config.vm.define vmName do |node|
      node.vm.box = "centos7"
      node.vm.network "private_network", ip: $workerNodeIps[n]
      node.vm.hostname = "node#{n}"
      node.vm.provider "virtualbox" do |vb|
        vb.memory = "1024"
        vb.cpus = "1"
        vb.name = "node#{n}"
      end
    end
  end
end

2. 启动

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vagrant up

3. 关闭

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vagrant halt

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1. 错误发生背景

在gitlab中初始化一个项目，并生成了README.md文件；本地已有代码进行合并时报错

2. 处理方法

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# merge命令附加--allow-unrelated-histories
git merge [feature/init] --allow-unrelated-histories # feature/init是已有代码开发分支

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1. Composer引入

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composer require illuminate/database
composer require illuminate/events

2. 创建DB操作类

文件可以创建为/library/DB.php, 内容如下:

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use Illuminate\Database\Capsule\Manager as Capsule;

$capsule = new Capsule;

// 注意修改此处的配置
$capsule->addConnection([
    'driver'    => 'mysql',
    'host'      => 'localhost',
    'database'  => 'database',
    'username'  => 'root',
    'password'  => 'password',
    'charset'   => 'utf8',
    'collation' => 'utf8_unicode_ci',
    'prefix'    => '',
]);

// Set the event dispatcher used by Eloquent models... (optional)
use Illuminate\Events\Dispatcher;
use Illuminate\Container\Container;
$capsule->setEventDispatcher(new Dispatcher(new Container));

// Make this Capsule instance available globally via static methods... (optional)
$capsule->setAsGlobal();

// Setup the Eloquent ORM... (optional; unless you've used setEventDispatcher())
$capsule->bootEloquent();

3. 使用DB操作类

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DB::table('table_name')->select();

4. 更多操作

https://laravel-china.org/docs/laravel/5.7/database/2288