random 10-digit code

[coolphpdude]

Hi there,

 

Is there a quick way of generating a random 10-digit code? it must be 10 digits long, no shorter, no longer.

[mbeals]

rand(1000000000,9999999999)

[dingus]

<?php 
       $key_characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'; 
        $licence_length = 10 ;
        for($i=0;$i<$licence_length;$i++){
            $chr = $key_characters[rand(0,strlen($key_characters))];
            $number .= $chr ;
        }
?>

 

thats should do it 

[coolphpdude]

You little star.

Cheers bud!

 

[discomatt]

<?php

$digits = 10;
$rand = '';

for ( $i = 0; $i < $digits; $i++ )
$rand .= mt_rand(0,9);

echo $rand;

?>

[dingus]

mbeals rand is limited to 32768

[coolphpdude]

is there a way to check to see if this random number already exists in the database and if it does then create an alternative random number?

[Lamez]

ya pull the data from the database, then check it and if the new number equals one of the other one, run it again.

[mbeals]

mbeals rand is limited to 32768

 

funny, my system had no problem with it

[coolphpdude]

both ways work a treat. I've gone with dingus's code because it combines numbers and both upper and lowercase code so gives me more chance of it being unique. I just need to figure out the code now to check database to see if it exists and if it does stick it in a while loop to generate a different code.

 

Thanks for your help guys, much appreciated.

[dingus]

just query the database and get the number of results if that is = its unique add it and move on else generate a new one you could probably use a recersive function call for that

[Barand]

mbeals rand is limited to 32768

 

Note: On some platforms (such as Windows) RAND_MAX is only 32768. If you require a range larger than 32768, specifying min and max will allow you to create a range larger than RAND_MAX, or consider using mt_rand() instead.

[mbeals]

Yea I read that... And it seems to say that specifying a randmax (like I did) higher then 32768 would work (like it did)

[chronister]

Here is one that uses sha1 and time which will most always be a unique code.

 

$code = substr(sha1(time()),0,10));

 

 

[rarebit]

it may be somewhat unique (have a low collision rate), but it depends what its going to be used for. Let's say it's generated when you register, if I know roughly when you registered I could generate the possibilities...

 

And i've just noticed, your only using the first 10 chars of the sha, well then there's no guarantee that it'll be unique!!!

[Barand]

Exactly, not what you'd call random

 

<?php
$a = array();
for ($i=0; $i<1000; $i++)  $a[] = substr(sha1(time()),0,10);

$ka = array_count_values($a);
echo '<pre>', print_r($ka, true), '</pre>';
?>

1000 generated and all the same

[chronister]

yeah, I noticed that if your generating a bunch at once, it will be the same.... but if your only using it once in a while as I am it is fine.

 

I am not using it for registration though..... I use it to pass a transaction to a gift card company and they pass it back. So if they match, then the transaction is valid if not I kill the transaction.

 

So, not the best solution for all situations, but it works for some.