CODEWITHSUNDEEP
phprandom
tanasi
tanasi

Reputation: 1804

Create 10,000 non-repeating random numbers in PHP

I need to work out a way to create 10,000 non-repeating random numbers in PHP, and then put it into database table. Number will be 12 digits long.

What is the best way to do this?

Upvotes: 0

Views: 4389

Answers (4)

dmcnelis
dmcnelis

Reputation: 2923

This assumes that you can generate a 12 digit random number without problems (use getrandmax() to see how big you can get....according to php.net on some systems 32k is as large a number as you can get.

$array = array();

while(sizeof($array)<=10000){
  $number = mt_rand(0,999999999999);
  if(!array_key_exists($number,$array)){
     $array[$number] = null;
  }
}

foreach($array as $key=>$val){
  //write array records to db.
}

You could use either rand() or mt_rand(). mt_rand() is supposed to be faster however.

Upvotes: -1

Flavius
Flavius

Reputation: 13816

Read e.g. 40000 (=PHP_INT_SIZE * 10000) bytes from /dev/random at once, then split it, modularize it (the % operator), and there you have it.

Then filter it, and repeat the procedure.

That avoids too many syscalls/context switches (between the php runtime, the zend engine, and the operating system itself - I'm not going to dive into details here).

That should be the most performant way of doing it.

Upvotes: 3

mpdonadio
mpdonadio

Reputation: 2941

Generate 10000 random numbers and place them in an array. Run the array through array_unique. Check the length. If less than 10000, add on a bunch more. Run the array through array_unique. If greater than 10000, then run through array_slice to give 10000. Otherwise, lather, rinse, repeat.

Upvotes: 1

Eric Petroelje
Eric Petroelje

Reputation: 60498

At 12 digits long, I don't think the possibility of getting repeats is very large. I would probably just generate the numbers, try to insert them into the table, and if it already exists (assuming you have a unique constraint on that column) just generate another one.

Upvotes: 4

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