Array creation with non-repeat values

[MFA]

Hi,

I'm trying to make an array containing values that are unique (i.e. the values are not repeated within the array). There seems to be a mistake somewhere in my code below because only one value (the first element of the array) is being stored in the $randommodulearray array. I would appreciate it if someone could explain why. Cheers.

Also, just to confirm, $module == 'all'.
 

if (($module == 'all') || ($module == 'sem1') || ($module == 'sem2'))
{
$modulearray = array("1"=>"Endocrine","2"=>"Renal","3"=>"Genetics","4"=>"GI","5"=>"Neuro","6"=>"EPISTATS");

$randommodulearray = array();

switch ($module)
{
case 'all':
$numberofmodules = '6';
$min = '1';
$max = '6';
break;

case 'sem1':
$numberofmodules = '3';
$min = '3';
$max = '6';
break;

case 'sem2':
$numberofmodules = '3';
$min = '1';
$max = '3';
break;


}

do
{
$optionmodule = rand($min,$max);
$checkmodule = $modulearray[$optionmodule];
if (in_array($checkmodule, $randommodulearray))
{
    do
    {
        echo 'lol';
        $optionmodule = rand($min,$max);
        $checkmodule = $modulearray[$optionmodule];
        
    }
    while (!in_array($checkmodule, $randommodulearray));
    
$randommodulearray[] = $checkmodule;
}
else
{

$randommodulearray[] = $checkmodule;
}
}
while (count($randommodulearray) == $numberofmodules); // i.e. until they are 6 elements in array


}

[requinix]

Does array_unique suit your needs better than writing something yourself?

[MFA]

I knew I could use the array_unique function but I decided to write something more neat. Do you have any ideas as to why my code doesn't work?

[requinix]

Neater? I don't see how that's neater. But after reading the code I wouldn't suggest using array_unique() anyways - wrong tool for the job.

 

What you have is a bit... off. The main problem is how you're doing the randomization. It's a very inefficient approach and there's something much better.

Try

if (in_array($module, array('all', 'sem1', 'sem2')))
{
	$modulearray = array(
		1 => 'Endocrine',
		2 => 'Renal',
		3 => 'Genetics',
		4 => 'GI',
		5 => 'Neuro',
		6 => 'EPISTATS'
	);

	switch ($module)
	{
		case 'all':
			$modules = array(1, 2, 3, 4, 5, 6);
			break;
		case 'sem1':
			$modules = array(4, 5, 6);
			break;
		case 'sem2':
			$modules = array(1, 2, 3);
			break;
	}

	shuffle($modules);

	$randommodulearray = array();
	foreach ($modules as $m)
	{
		$randommodulearray[] = $modulearray[$m];
	}
}

But to answer the question,

while (count($randommodulearray) == $numberofmodules)

Think about exactly what's happening there. What will happen after $randommodulearray has its first item?

[MFA]

Ahhh, I never knew of the shuffle function. Very useful in this scenerio indeed.

 

while (count($randommodulearray) == $numberofmodules)

Think about exactly what's happening there. What will happen after $randommodulearray has its first item?

 

It should have been:

while (count($randommodulearray) != $numberofmodules)

Thanks for your help.