PHP generation unique ID several workarounds _php tutorial

There's a lot of ways to check it online.

1, MD5 (Time (). Mt_rand (1,1000000));

This method has a certain probability that there will be repetition

2. PHP built-in function uniqid ()

The Uniqid () function generates a unique ID based on the current time in microseconds.

W3school Reference Manual There is a sentence: "Due to system time, the ID generated by this function is not optimal." To generate an absolutely unique ID, use the MD5 () function.

The following method returns the result similar to: 5ddb650f-4389-f4a9-a100-501ef1348872

copy code code as follows:
function uuid () {
if (function_exists (' Com_create_guid ')) {
return com_create_guid ();
} else {
Mt_srand (double) microti Me () * 10000); Optional for PHP 4.2.0 and up. The random number sowing, 4.2.0 not need after.
$charid = Strtoupper (MD5 (Uniqid (rand (), true)), and//generates a unique ID based on the current time (in microseconds).
$hyphen = CHR;//"-"
$uuid = ".//CHR (123)//" {"
substr ($charid, 0, 8). $hyphen. SUBSTR ($charid, 8, 4). $hyphen. SUBSTR ($charid, 12, 4). $hyphen. SUBSTR ($charid, 16, 4). $hyphen. SUBSTR ($charid, 20, 12);
//.CHR;//"}"
return $uuid;
} The
}

Com_create_guid () is a PHP-generated unique ID method that appears to be out of PHP5.
3, the official uniqid () reference manual has the user-provided method, the result is similar: {E2DFFFB3-571E-6CFC-4B5C-9FEDAAF2EFD7}

Copy the Code code as follows:
Public Function create_guid ($namespace = ") {
static $guid = ';
$uid = Uniqid ("", true);
$data = $namespace;
$data. = $_server[' request_time ');
$data. = $_server[' http_user_agent ');
$data. = $_server[' local_addr ');
$data. = $_server[' Local_port ');
$data. = $_server[' remote_addr ');
$data. = $_server[' Remote_port ');
$hash = Strtoupper (hash (' ripemd128 ', $uid. $guid. MD5 ($DATA)));
$guid = ' {'.
substr ($hash, 0, 8).
'-' .
SUBSTR ($hash, 8, 4).
'-' .
SUBSTR ($hash, 12, 4).
'-' .
SUBSTR ($hash, 16, 4).
'-' .
SUBSTR ($hash, 20, 12).
'}';
return $guid;
}

http://www.bkjia.com/PHPjc/326742.html www.bkjia.com true http://www.bkjia.com/PHPjc/326742.html techarticle Online Search, there are a lot of methods 1, MD5 (Time (). Mt_rand (1,1000000)); This method has a certain probability of repeating 2, PHP built-in Functions uniqid () uniqid () function based on microseconds ...

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