array_diff()

[NLCJ]

Hello,

I'm trying to create a little function that randomly selects the winners, then it has to remove the winners from the array where it was in. I created it like this:

$participants = array();
function winners($participants, $roundnumber, $amount) {
$roundnumberwinners = $winners.$roundnumber;
$roundnumberwinners = array_rand($participants, $amount);
//print_r($roundnumberwinners);
//echo "<br />";
$values = array();
foreach($roundnumberwinners as $key => $value) {
	$values[] = $roundnumberwinners[$participants[$value]];
}

//echo $roundnumber." - ".count($participants)."<br />";
$participants = array_diff($participants, $values);
echo $roundnumber." - ".count($participants)."<br />";
}

 

It perfectly selects the amount of winners I want, but it doesn't get them out of the original array ($participants). I call it with:

$winnerstest = winners($participants, 1, 10);

 

If anyone could help... I've been stuck on this for a few days now.

 

Thanks,

Chris

[AMcHarg]

Shuffle your array, select the first as the winner and then severe that one from the array. 

 

Edit: Or where you want more than one winner, select the first however many from the array and then remove them from the array. Shuffling the array randomizes their order in the array, so selecting the first few in the array after it has been shuffled will always pull out random results.

[NLCJ]

How do I remove them from the array? That's kind of my problem. 

[HDFilmMaker2112]

How do I remove them from the array? That's kind of my problem. 

 

How many are you trying to take off, array_shift will remove the first item in the array, and shift everything else down.

 

http://www.php.net/manual/en/function.array-shift.php

[NLCJ]

I get 10 random items from the array, I also want to remove those exact 10. Every item in the array is unique, so it should be possible, right?

 

Because every item in the array is unique, I thought I could easily differ it from the rest. Either my thoughs are wrong or my code.

[HDFilmMaker2112]

Maybe array_slice or array_splice?

 

http://www.php.net/manual/en/function.array-slice.php

 

http://www.php.net/manual/en/function.array-splice.php

[AMcHarg]

Try the below as an alternative to your method. It should produce a random winner and then remove that player from the array. The same principal will work if more winners are required.

 

$players = array("Player1","Player2","Player3","Player4");
shuffle($players);
$winner = $players[0];
$players = array_slice($players, 1);

[NLCJ]

Okay, I'm trying to use slice, but cannot get it to work;

function winners($array, $roundnumber, $amount) {
echo $roundnumber." ".$amount." - ";
$winners.$roundnumber = array();
shuffle($array);
for($i = 0; $i < $amount; $i++) {
	$winners.$roundnumber[] = $array[$i];
}
$array = array_slice($array, $amount);
shuffle($array);
echo count($array)."<br />";
}

I know the second shuffle isn't necessary, it just gives me a better feeling. I also replaces $participants with $array, since the array with participants was called $participanst, this was confusing.

 

What isn't working? Well, the array gets more items in it, 1 per time I call it... 

[AMcHarg]

$array = array_slice($array, 0, $amount, false);

 

Simply having array_slice on it's own doesn't work in the same way as it does with shuffle. 

 

Edit: Hey you changed it when I was writing the above! Is it still not working? 

[NLCJ]

Yup, I edited it.

 

function winners($array, $roundnumber, $amount) {
echo $roundnumber." ".$amount." - ";
$winners.$roundnumber = array();
$array = shuffle($array);
for($i = 0; $i < $amount; $i++) {
	$winners.$roundnumber[] = $array[$i];
}
$array = array_slice($array, $amount);
$array = shuffle($array);
echo count($array)."<br />";
//print_r($winners.$roundnumber);
}

 

Nope, still not working... I get the following errors:

Warning: array_slice() expects parameter 1 to be array, boolean given in ... on line 34

Warning: shuffle() expects parameter 1 to be array, null given in ... on line 35

 

Cannot figure out what's wrong...

 

[AMcHarg]

$winners.$roundnumber[] = $array[$i];

 

Does this line actually work? It's meant to be a variable variable... right? I thought you required two $ at the beginning...

 

$$winners.$roundnumber[] = $array[$i];

 

Might not be connected to the errors you are receiving though.

[AbraCadaver]

Try this (make sure to use the &).  I don't see why you need the $roundnumber:

 

function winners(&$participants, $amount) {
   shuffle($participants);
   return array_splice($participants, 0, $amount);
}
$winnerstest = winners($participants, 10);

[NLCJ]

Thank you, the & did the trick!

 

And thanks to all others who helped me, too!