Creating a unique number from a time stamp PHP

Does it have to be 20, can it not be 32 characters long?

As you could create the md5 hash of a timestamp, should be unique unless two get generated at exactly the same time.

The function time() "Returns the current time measured in the number of seconds since the Unix Epoch (January 1 1970 00:00:00 GMT).", aka a large integer of 10 places. How precise do you need it? This one obviously won't work if you need finely granularity than seconds on the unique ids.... but it works just fine in situations like I use it: measure temperatures every two minutes.

hi,


http://www.htmlite.com/php012.php

http://www.php-scripts.com/php_diary/122799.php3

As far as I can tell, you need two pieces, a random bit and the timestamp, if you want it to be based on timestamp + unique with finer than second granularity.

Akin to the unix command date '+%s%N', using a timestamp + a random number should do the trick:

srand ((double) microtime( )*10000000000);
$random_number = rand( );
$uniqueID = time().$random_number;

// or the lazy way:
$uniqueID = exec("date '+%s%N'");

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You can try uniqueid() (value of true extends the length

http://www.php.net/manual/en/function.uniqid.php

To get to 20 chars you can take the least significant 20 bytes.

*microtime( )*10000000000 should be microtime( )*1000000. Too many 0s.....

If you want alpha-numeric characters, uniqid will work.

Thanks for all the answers.

Solution by marklogan did the job perfectly since it turns out the length has to be exactly 20 characters.

Many thanks,
Dan