help declaring and testing an array

Worker Joined: Feb 18, 2004 Posts: 244

Hi,

I'm trying to write a function that draws cards from a deck contained virtually within a database.

I do not want the function to return duplicate cards. So I need a function that tests an array of intigers to see if one already exists.

What function do you use to see if an intiger already exists within an array?

Here's what I have:

Code:

function draw($num) {


   global $db, $prefix;


   mt_srand((double)microtime() * 1000000); // Seed the generator 


   $counter=0;


   $cards = array( 0 => '0' );  // Do I need to do this to ensure that $cards will be an array?


      


   list($total) = $db->sql_fetchrow($db->sql_query("SELECT count(*) FROM ".$prefix."_rtc")); 





   while ($counter <= ($num-1)) {


      $num1 = rand(0,($total-1)); 


      list($id) = $db->sql_fetchrow($db->sql_query("SELECT id FROM ".$prefix."_rtc LIMIT $num1,1"));


// I need a test here that says while $id is not in $cards go ahead and add it. If it is in the cards don't add it and instead incriment the $counter by one so that we draw another card. Does such a function exist? How do you use it?


      $cards[$counter]=$id;


      $counter=$counter+1;


   }





   return $cards;


}

Thanks for your suggestions. I appreciat them all.

Darrell

Site Admin/Owner Joined: Aug 27, 2002 Posts: 17088

in_array()

Posted: Wed Jun 29, 2005 12:02 pm

Thank you!

That's perfect. I just don't know the names of these things..

Code:

function draw($num) {


   global $db, $prefix;





   mt_srand((double)microtime() * 1000000); // Seed the generator 


   $counter=0;


   $cards = array( 0 => NULL );  


      


   list($total) = $db->sql_fetchrow($db->sql_query("SELECT count(*) FROM ".$prefix."_rtc")); 





   while ($counter <= ($num-1)) {


      $num1 = rand(0,($total-1));


      if (in_array($num1, $cards))  {


         if ($counter != 0) {


            $counter=$counter-1;


         }


      }


      else {


         list($id) = $db->sql_fetchrow($db->sql_query("SELECT id FROM ".$prefix."_rtc LIMIT $num1,1"));


         $cards[$counter]=$id;


      }


      $counter=$counter+1;


   }


   return $cards;


}

Darrell

Posted: Fri Jul 01, 2005 4:16 pm

I spoke too soon. Sad

It's still allowing duplicates.

Does anyone see what might be wrong with the way I'm using in_array()?

Thanks!

Code:

function draw($num) {


   global $db, $prefix;





   mt_srand((double)microtime() * 1000000); // Seed the generator 


   $counter=0;


   $cards = array( 0 => '-1' );  


   


   list($total) = $db->sql_fetchrow($db->sql_query("SELECT count(*) FROM ".$prefix."_rtc")); 





   while ($counter <= ($num-1)) {


      $num1 = rand(0,($total-1));


      if (in_array($num1, $cards))  {


         if ($counter != 0) {


            $counter=$counter-1;


         }


      }


      else {


         list($id) = $db->sql_fetchrow($db->sql_query("SELECT id FROM ".$prefix."_rtc LIMIT $num1,1"));


         $cards[$counter]=$id;


      }


      $counter=$counter+1;


   }


   return $cards;


}

Posted: Mon Jul 18, 2005 5:40 am

Resolved...

Posted: Mon Jul 18, 2005 7:16 am

For posterity, would you share the "resolved" code?

Posted: Mon Jul 18, 2005 11:54 am

Sure,

I'd be happy to. I just assumed no one was interested...

It was my fault of course, I had the logic wrong. Very Happy

Code:

function draw($num) {


   global $db, $prefix;





   mt_srand((double)microtime() * 1000000); // Seed the generator 


   $counter=0;


   $cards = array( 0 => -1 );  


   


   list($total) = $db->sql_fetchrow($db->sql_query("SELECT count(*) FROM ".$prefix."_rtc")); 





   while ($counter <= ($num-1)) {


      $num1 = rand(0,($total-1));


      list($id) = $db->sql_fetchrow($db->sql_query("SELECT id FROM ".$prefix."_rtc LIMIT $num1,1"));


      if (in_array($id, $cards))  {


         if ($counter > 0) {


            $counter=$counter-1;


         }


      }


      else {


         $cards[$counter]=$id;


      }


      $counter=$counter+1;


   }


   return $cards;


}

Thanks,
Darrell