PHP If/ELSE or Switch/Case Statement

Question

I have give inputs which can be either 1 or 0

$no_required
$on_arrival
$schengen_visa
$uk_visa
$usa_visa

I have the Following Cases and i want to display unique message back to the user for each one of them

a b c d e
1 0 0 0 0   No Visa Required
0 1 0 0 0   Visa can be obtained on Arrival
0 0 1 0 0   You need Schengen Visa
0 0 0 1 0   You need UK visa
0 0 0 0 1   You need US visa
0 0 1 1 1   You need Either of the Visas
0 0 1 1 0   You need Schengen/UK visa
0 0 1 0 1   You need Schengen/US visa
0 0 0 1 1   You need USA/UK visa

Where A B C D E F are the above variables. Which is the best and optimized way to display the results.

Answer 1

The conditions you're showing can very nicely be modeled via bit masks:

$messages = [
    16 => 'No Visa Required',
    8  => 'Visa can be obtained ...',
    4  => ...
];

You then just have to format your separate variables into a bitmask:

$bitmask = ($no_required ? 16 : 0)
         | ($on_arrival  ? 8  : 0)
         | ...;

Then just pick the right message:

echo $messages[$bitmask];

---

Note: use of constants instead of magic numbers is pretty much mandatory here as well, so it'd look like this:

define('VISA_NONE',       1);
define('VISA_ON_ARRIVAL', 2);
...

$messages = [
    VISA_NONE         => 'No Visa Required',
    ...,
    VISA_US | VISA_UK => 'You need USA/UK visa'
];

// using multiplication instead of conditionals, as mentioned in the comments
$bitmask = $no_required * VISA_NONE
         | $on_arrival  * VISA_ON_ARRIVAL
         | ...;

echo $messages[$bitmask];

---

Wrap the whole thing in an appropriate class and you have yourself a nice, readable, maintainable, reusable piece of business logic:

class Visa {

    const NONE       = 1;
    const ON_ARRIVAL = 2;
    ...

    protected $messages = [];

    protected $visa;

    public function __construct() {
        $this->messages = [
            static::NONE            => 'No Visa Required',
            ...,
            static::US | static::UK => 'You need USA/UK visa'
        ];
    }

    /**
     * @param int  $type    One of the class constants.
     * @param bool $enabled Whether this type of visa is required.
     */
    public function set($type, $enabled) {
        $this->visa = $this->visa | $type * (int)(bool)$enabled;
    }

    public function getMessage() {
        return $this->messages[$this->visa];
    }

}


$visa = new Visa;
$visa->set($visa::NONE,       $no_required);
$visa->set($visa::ON_ARRIVAL, $on_arrival);

echo $visa->getMessage();