I. Introduction of GUIDs
GUID: The globally unique Identifier (globally unique identifier) is also known as the UUID (universally unique Identifier). A GUID is a 128-bit numeric identifier produced by a particular algorithm that indicates the uniqueness of the product. GUIDs are primarily used to assign identifiers that must be unique in a network or system that has multiple nodes, multiple computers, and more than one computer.
On the Windows platform, GUIDs are widely used in Microsoft products to identify objects such as registry keys, class and interface identifiers, databases, system catalogs, and so on.
The format of the GUID is "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx", where each x is a 32-bit hexadecimal number in the range of 0-9 or a-f. For example, 6F9619FF-8B86-D011-B42D-00C04FC964FF is a valid GUID value.
second, the advantages of the GUID
The 1.GUID is unique in space and time, ensuring that the numbers produced at different places at the same time are different.
2. No two computers in the world will generate duplicate GUID values.
3. When a GUID is required, it can be automatically generated by the algorithm and does not require an authoritative authority to manage it.
The 4.GUID is fixed in length and relatively short, and is ideal for sorting, labeling, and storage.
third, GUID generation function
Copy CodeThe code is as follows:
function Create_guid () {
$charid = Strtoupper (MD5 (Uniqid (Mt_rand (), true));
$hyphen = Chr (45);//"-"
$uuid = Chr (123)//"{"
. substr ($charid, 0, 8). $hyphen
. substr ($charid, 8, 4). $hyphen
. substr ($charid, 4). $hyphen
. substr ($charid, 4). $hyphen
. substr ($charid, 20,12)
. chr (125);//"}"
return $uuid;
}
third, GUID generation class
PHP Gets the GUID class: guid_class.php
Copy CodeThe code is as follows:
Class System
{
function Currenttimemillis ()
{
List ($usec, $sec) = Explode ("", Microtime ());
Return $sec. substr ($usec, 2, 3);
}
}
Class Netaddress
{
var $Name = ' localhost ';
var $IP = ' 127.0.0.1 ';
function Getlocalhost ()//static
{
$address = new Netaddress ();
$address->name = $_env["COMPUTERNAME"];
$address->ip = $_server["Server_addr"];
return $address;
}
function toString ()
{
Return Strtolower ($this->name. ' /'. $this->ip);
}
}
Class Random
{
function Nextlong ()
{
$tmp = rand (0,1)? ' -':'';
Return $tmp. Rand (9999). RAND (9999, 9999) rand (+, 999). RAND (100, 999);
}
}
Three sections
A section of a microsecond is an address, a random number.
Class Guid
{
var $valueBeforeMD 5;
var $valueAfterMD 5;
function Guid ()
{
$this->getguid ();
}
//
function GetGuid ()
{
$address = Netaddress::getlocalhost ();
$this->valuebeforemd5 = $address->tostring (). ': '. System::currenttimemillis (). ': '. Random::nextlong ();
$this->VALUEAFTERMD5 = MD5 ($this->valuebeforemd5);
}
function NewGuid ()
{
$Guid = new Guid ();
return $Guid;
}
function toString ()
{
$raw = Strtoupper ($this->valueaftermd5);
Return substr ($raw, 0,8). ' -'. substr ($raw, 8,4). ' -'. substr ($raw, 12,4). ' -'. substr ($raw, 16,4). ' -'. substr ($raw, 20);
}
}
How to use the GUID class:
Copy the Code code as follows:
Require_once ("guid.class.php");
$Guid = new Guid ();
Print $Guid->tostring ();
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