How to Generate Random Numbers?

[jhl84]

Hi guys, i have this number, 878777886XXXXXX. The Xs represent random numbers that I want to generate. I want to generate 1000 numbers that does not repeat using php. can anyone help?

 

thanks!

[chronister]

http://us2.php.net/manual/en/function.rand.php

 

Random Function is what your looking for

[Daney11]

Hey mate, I think this is what you are looking for....

 

<?php

for ($i=1; $i <= 10; $i++)

{

$number_start = "878777886";

$number_rand = mt_rand(100000, 999999); // XXXXXX = 6 Digits

$number = "$number_start$number_rand";

echo $number.'<br />';

}

?>

 

Just change the 10 in the for loop for 1000 or what ever number you want.

[kenrbnsn]

Neither one of the the above solutions guarantee that the random numbers will not repeat. That can be done with the following code:

<?php
$ok_rand = array();
for ($i=0;$i<1000;$i++) {
     $test_rand = rand(1,999999);   // get a random number
     while(in_array($test_rand,$ok_rand)) $test_rand =  rand(100000,999999);  // have we seen this number already? Yes -- generate another
     $ok_rand[$i] = sprintf('%06d',$test_rand); // store unique number as a six digit number with leading zeros
}
//
// use the stored numbers
//
?>

 

Ken

[boo_lolly]

actually ken, if i've understood your code correctly, it doesn't ensure that the numbers won't repet either. although the probability is very slim, it is still possible that it would generate the same number twice in a row. here is some code that will make sure there's not a repeat.

<?php
        $input = 878777886 . rand(100000, 999999);
        $rand_array = array();

        for($i = 0; $i < 1000; $i++){
                foreach($rand_array as $key => $val){
                        (($input != $val) ? ($bool = false) : ($bool = true)); 
                }       
                (($bool == false) ? ($rand_array[] = $input) : ($i--));
        }       
        print_r($rand_array);
?> 

 

untested.

 

i'm curious... will the value of $input constantly change, or will it stay the same? i'm not sure how that works...

[Daney11]

Hi boo_lolly..

 

Not that i needed this i just fancied testing the 2 codes you 2 have posted and i tested yours with only 10 results wanting to be displayed and got...

 

Notice: Undefined variable: bool in c:\www\test\milk.php on line 9

 

Fatal error: Maximum execution time of 30 seconds exceeded in c:\www\test\milk.php on line 7

[boo_lolly]

Hi boo_lolly..

 

Not that i needed this i just fancied testing the 2 codes you 2 have posted and i tested yours with only 10 results wanting to be displayed and got...

 

Notice: Undefined variable: bool in c:\www\test\milk.php on line 9

 

Fatal error: Maximum execution time of 30 seconds exceeded in c:\www\test\milk.php on line 7

 

hmmmmm... maybe there's a better way to approach this...

<?php
<?php
        $rand_array = array();

        for($i = 0; $i < 1000; $i++){
                $input = 878777886 . rand(100000, 999999);
                foreach($rand_array as $key => $val){
                        (($input != $val) ? ($bool = false) : ($bool = true; exit;));
                }       
                (($bool == false) ? ($rand_array[] = $input) : ($i--));
        }       
        print_r($rand_array);
?> 
?>

[boo_lolly]

or how about this....

<?php
        $rand_array = array();
        for($i = 100000; $i < 999999; $i++){
                $rand_array[] = $i;
        }       
        shuffle($rand_array);
        
        $i = 0;
        $append_array = array();
        foreach($rand_array as $key => $val){
                $append_array[] = 878777886 . $val;
                (($i < 1000) ? (continue) : (exit));
                $i++;
        }
        print_r($append_array);
?> 

[Daney11]

Nope boo_lolly, Both of them giving out parse error's on line 7 and 8.

 

<?php
        $rand_array = array();
        for($i = 100000; $i < 999999; $i++){
                $rand_array[] = $i;
        }       
        shuffle($rand_array);
        
        $i = 0;
        $append_array = array();
        foreach($rand_array as $key => $val){
                $append_array[] = 878777886 . $val;
                (($i < 1000) ? (continue) : (exit));
                $i++;
        }
        print_r($append_array);
?>

 

this one is giving out parse error on line 12 which is

 

(($i < 1000) ? (continue) : (exit));

 

 

[boo_lolly]

i don't understand why the second one would be giving a parse error... what's the exact error? and for what code?

[Daney11]

I just says

 

Parse error: parse error in c:\test\milk.php on line 12

 

not sure how to use error reporting in scripts... might have to start using it lol.

[boo_lolly]

try doing this, and see if it gives an error:

<?php
        $val = 10101;
        echo 84718947491 . $val;
?>

if it brings an error, then that's the problem. appending an intiger to an existing integer.

[Daney11]

that works fine mate

[boo_lolly]

ok meow:

<?php
        $rand_array = array();
        for($i = 100000; $i < 999999; $i++){
                $rand_array[] = $i;
        }       
        shuffle($rand_array);
        
        $i = 0;
        $append_array = array();
        foreach($rand_array as $key => $val){
                $append_array[] = 878777886 . $val;
                if($i < 1000){
                        continue;
                }else{
                        exit;
                }
                $i++;
        }       
?>      

 

this is, in theory, no different than the previous code... but try it and see if that works.

[Daney11]

Not outputting anything to the browser.

[boo_lolly]

it's not supposed to. but the values are stored in the array, perfectly, i bet.

[kenrbnsn]

Just came back to the conversation.

 

My original code works fine.

 

The trick is the while statement within the for loop. It will loop until a random number is generated that is not in the array.

 

To check, add these three lines to the end of my script:

<?php
$unq = array_unique($ok_rand);
$dif = array_diff($ok_rand,$unq);
if (empty($dif)) echo "All generated random numbers are unique";
?>

 

Ken

[boo_lolly]

well, it looks like i didn't understand your code correctly =\