PHP endless loop, why? - php

Question

Here is my code. I don't understand why am I in endless loop.
I think $check has to stop the loop when I make unique random values for my array.
<?php
$foo["blue"] = 0;
$foo["black"] = 0;
$foo["red"] = 0;
$foo["white"] = 0;
$check;
do
{
foreach($foo as &$val)
{
$val = rand(1,6);
}
$foo = array_unique($foo);
$check = count($foo);
}
while($check != 4);
echo '............................ <br>';
foreach($foo as $key=>$value)
{
echo $key . ' ' . $value . '<br>';
}
?>

Answer 1

The problem is that the first time through the loop there are some duplicates, so array_unique() reduces the array from 4 elements to 1, 2, or 3. The foreach loop can never make the array bigger again, because it's only looping over the elements that currently exist in the array. So once the array shrinks, it will never grow back to 4 elements, and $check != 4 will always be true.
You should get the original keys of the array and use that.
<?php
$foo["blue"] = 0;
$foo["black"] = 0;
$foo["red"] = 0;
$foo["white"] = 0;
$keys = array_keys($foo);
$check;
do
{
foreach($keys as $i)
{
$foo[$i] = rand(1,6);
}
$foo = array_unique($foo);
$check = count($foo);
}
while($check != 4);
echo '............................ <br>';
foreach($foo as $key=>$value)
{
echo $key . ' ' . $value . '<br>';
}
?>
DEMO

Answer 2

Personally, I wouldn't do it in a loop with such low entropy as it could take all day to finally match a random set.
A better way would be to generate a range and randomise that, then loop over your array and set the value.
<?php
$rand = range(1, 6);
shuffle($rand);
$foo["blue"] = 0;
$foo["black"] = 0;
$foo["red"] = 0;
$foo["white"] = 0;
$i=0;
foreach ($foo as $key => $value) {
$foo[$key] = $rand[$i];
$i++;
}
print_r($foo);
/*Array
(
[blue] => 1
[black] => 3
[red] => 2
[white] => 5
)
*/
https://3v4l.org/4hPku