php generates a unique membership number

Without querying the database, each member who logs in will generate a membership card number with a unique combination of numbers and letters.

The rendering is as follows:

#When we want to number a huge data, and the number has a limit on the number of digits, For example, a 5-digit license plate number, a 10-digit document number, an order serial number, a short URL, etc., we can use hexadecimal to calculate a unique number that matches the number of digits.

We use 0-Z (0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ) to represent values ​​0-35 respectively, such as the letter Z representing 35. In this case, I want to get a 5-digit number. The maximum amount of information is 36 raised to the fifth power, 36^5 = 60466176, that is, the maximum 5-digit number is equivalent to a decimal number: 60466176.

For the sake of demonstration in this article, we assume that a club issues a batch of 10-digit membership card numbers. The membership card number consists of a 3-digit city number, a 5-digit card number code, and a 2-digit check code. The city number is represented by the area code. For example, 755 represents Shenzhen. The 5-digit card number is composed of a 36-digit card number. The next two check codes are generated through a certain algorithm. The purpose of the check code is to verify the card number. legality. In this case, the 10-digit card number we generate is equivalent to a maximum of more than 60 million membership card numbers, and it is a unique card number that does not repeat.

PHP

We use PHP to convert decimal to hexadecimal.

class Code { 
 //密码字典 
 private $dic = array( 
 0=>'0', 1=>'1', 2=>'2', 3=>'3', 4=>'4', 5=>'5', 6=>'6', 7=>'7', 8=>'8', 
 9=>'9', 10=>'A', 11=>'B', 12=>'C', 13=>'D', 14=>'E', 15=>'F', 16=>'G', 17=>'H', 
 18=>'I',19=>'J', 20=>'K', 21=>'L', 22=>'M', 23=>'N', 24=>'O', 25=>'P', 26=>'Q', 
 27=>'R',28=>'S', 29=>'T', 30=>'U', 31=>'V', 32=>'W', 33=>'X', 34=>'Y', 35=>'Z' 
 ); 
 public function encodeID($int, $format=8) { 
 $dics = $this->dic; 
 $dnum = 36; //进制数 
 $arr = array (); 
 $loop = true; 
 while ($loop) { 
  $arr[] = $dics[bcmod($int, $dnum)]; 
  $int = bcdiv($int, $dnum, 0); 
  if ($int == '0') { 
  $loop = false; 
  } 
 } 
 if (count($arr) < $format) 
  $arr = array_pad($arr, $format, $dics[0]); 
 return implode(&#39;&#39;, array_reverse($arr)); 
 } 
 public function decodeID($ids) { 
 $dics = $this->dic; 
 $dnum = 36; //进制数 
 //键值交换 
 $dedic = array_flip($dics); 
 //去零 
 $id = ltrim($ids, $dics[0]); 
 //反转 
 $id = strrev($id); 
 $v = 0; 
 for ($i = 0, $j = strlen($id); $i < $j; $i++) { 
  $v = bcadd(bcmul($dedic[$id { 
  $i } 
  ], bcpow($dnum, $i, 0), 0), $v, 0); 
 } 
 return $v; 
 } 
}

We define the Code class and first define the password dictionary, that is, the values ​​corresponding to 0-Z. The parameter $int in the method encodeID($int, $format) represents the number, and $format represents the number of digits. Length, for example, encodeID(123456789,5) means converting the number 123456789 into a 5-digit 36-digit number, and the method decodeID($ids) is used to convert the 36-digit number into a decimal number.

We can generate the card number like this:

$code = new Code(); 
$card_no = $code->encodeID(888888,5);

As above, we can get a 5-digit card number, which actually represents the card number 888888 (6 8s) Member number, but after actual conversion it is a 5-digit number: 0J1VC.

Next, we add the city number and check code. The city number has been defined, and the check code is obtained through a certain algorithm. In this example, we use a simple algorithm: add the first three The city number and the five-digit card number are md5 encrypted, and then the first two digits of the md5 value are taken as the check code, so that the two-digit check code after the number is obtained.

$card_pre = '755'; 
$card_vc = substr(md5($card_pre.$card_no),0,2); 
$card_vc = strtoupper($card_vc); 
echo $card_pre.$card_no.$card_vc;

In actual application, the decimal number can be obtained through the database to ensure that the number is unique, and then the above codes are combined to finally generate a 10-digit non-duplicate membership card number.

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