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PHP uniqid() Function

PHP Misc Reference Complete PHP Misc Reference

Definition and Usage

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

Syntax

uniqid(prefix,more_entropy)

Parameter Description
prefix Optional. Specifies a prefix to the unique ID (useful if two scripts generate ids at exactly the same microsecond)

Note: This parameter became optional in PHP 5
more_entropy Optional. Specifies more entropy at the end of the return value. This will make the result more unique. When set to TRUE, the return string will be 23 characters. Default is FALSE, and the return string will be 13 characters long

Tips and Notes

Note: The generated ID from this function is not optimal, because it is based on the system time. To generate an extremely difficult to predict ID, use the md5() function (can be found in the String reference).

Example

<?php
echo uniqid();
?>

The output of the code above could be:

4415297e3af8c

PHP Misc Reference Complete PHP Misc Reference
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