How to compare arrays with different sizes

Question

I want to compare 2 arrays, except the two arrays may sometimes be of different sizes.

For example, I have a form and I receive the values with this:

// The post send more values than other array:
//   name , email , password, phone , address
// but in other cases send only one value and the other array it's bigger
foreach($_POST as $key=>$value)
{    
    $fields_array[]=$key;    
}

On the other side, I have this other array that I want to compare against:

    $fields_compare=array("name","email");

In this case when the array called $fields_array is the larger one, I don't have a problem. However, if for example the second array is larger, I have problems.

I continued and did this:

$aa=array_diff($fields_array,$fields_compare);
$bb=array_intersect($fields_array,$fields_compare);

foreach ($aa as $aaa)
{
    // Show the others different values, no show name and email
    print "".$aaa."<br>";
}

foreach ($bb as bbb)
{
    // Show the same Values in this case the same will be name and email ///
    print "".$bbb."<br>";
}

All this works if the first array is larger, but in other cases it doesn't work and doesn't show the real differences.

Answer 1

I'm not sure if this is what you're after, but what about just testing the input value types as you loop through the POST'd values?

$fields_compare=array("name" => true, "email" => true); //faster than in_array( );
foreach($_POST as $key=>$value)
{    
    if(isSet($fields_compare[$key]))
    {
        //do something (eg: save $value to text file)
    }
}