How to understand php GUID generating functions and classes

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A brief introduction to GUID

GUID: Globally Unique Identifier (globally unique identifier) is also known as UUID (Universally Unique IDentifier). GUID is a numeric identifier with a binary length of 128 bits generated by a specific algorithm to indicate the uniqueness of the product. GUID is mainly used to assign identifiers that must be unique in a network or system with multiple nodes and computers.

On the Windows platform, GUID is widely used in Microsoft products to identify objects such as registry entries, class and interface identifiers, databases, system catalogs and so on.

The format of GUID is "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx", where each x is a 32-bit hexadecimal number in the range of 0-9 or Amurf. For example, 6F9619FF-8B86-D011-B42D-00C04FC964FF is a valid GUID value.

Second, the advantages of GUID

1.GUID is unique in space and time, which ensures that the numbers generated in different places at the same time are different.

two。 No two computers in the world will generate duplicate GUID values.

3. When GUID is needed, it can be generated automatically by the algorithm and does not need to be managed by an authority.

4.GUID is fixed in length and relatively short, making it ideal for sorting, identification, and storage.

3. GUID generating function

The copy 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,12, 4). $hyphen

.substr ($charid,16, 4). $hyphen

.substr ($charid,20,12)

.chr (125); / / "}"

Return $uuid

}

Third, GUID generates classes

PHP gets the GUID class: guid_class.php

The copy code is as follows: