A better way than using multiple elseif statements? - php

Question

Is there a cleaner way to achieve a similar result, but without using all of these elseif statements? I need there to always be a true statement, depending on dynamic variables. Thanks!
$a = true;
$b = false;
$c = false;
if ($a == true && $b == false && $c == false) {
echo 'only $a is running';
} elseif ($a == true && $b == false && $c == true) {
echo '$a and $c are running, but not $b';
} elseif ($a == true && $b == true && $c == false) {
echo '$a and $b are running, but not $c';
} elseif ($a == false && $b == true && $c == true) {
echo '$b and $c are running, but not $a';
} elseif ($a == false && $b == false && $c == true) {
echo 'only $c is running';
} elseif ($a == false && $b == true && $c == false) {
echo 'only $b is running';
} else {
echo 'nope';
};

Answer 1

Consider to use an array, that way you can make more alphabet letters than you have in your example right now, and it will just work:
<?php
$arr = [
'a' => true,
'b' => true,
'c' => true
];
$running = [];
$not_running = [];
foreach($arr as $key=>$val)
if ($val)
$running[] = $key;
else
$not_running[] = $key;
if (count($running) == 0)
echo "Nope";
else if (count($running) == 1)
echo "Only ".$running[0]." is running";
else if (count($not_running) == 0)
echo "All are running";
else
echo "Only " . implode($running, ' and ') . " are running, but not ". implode($not_running, ' and ');
So now you can make your array bigger, for example like this:
for($i=0; $i<=25; $i++)
{
$arr[chr($i+97)] = (bool)rand(0,1);
}
which will output something like:
Only c and d and e and f and g and h and l and m and n and q and u and w and y and z are running, but not a and b and i and j and k and o and p and r and s and t and v and x

Answer 2

Here is one potential way you could do it by utilising __toString(), it's pretty rushed so you'll probably want to clean it up a bit. You can find a working example here
You may want to play with the __toString() return to get it to what you want, but essentially you just have to echo the collection.
Side note: I didn't implement Countable, ArrayAccess, Iterator or any other useful inbuilt interfaces due to time constraints. If you were to use this solution i'd suggest implementing them
<?php
class Instance
{
/** #var string */
private $name;
/** #var bool */
private $active;
public function __construct($name, $active = false)
{
$this->name = $name;
$this->active = $active;
}
public function turnOn()
{
$this->active = true;
}
public function turnOff()
{
$this->active = false;
}
public function getName()
{
return $this->name;
}
public function getActive()
{
return $this->active;
}
public function __toString()
{
$state = $this->getActive() === true ? 'on' : 'off';
return sprintf("%s is switched %s", $this->getName(), $state);
}
}
class InstanceCollection
{
private $collection = [];
public function add(Instance $item)
{
$this->collection[] = $item;
}
public function __toString()
{
$on = $this->getInstancesByState(true);
$off = $this->getInstancesByState(false);
return rtrim(implode(', ', $on), ', ') . rtrim(implode(', ', $off), ', ');
}
public function getInstancesByState($state)
{
return array_map(function($instance) use ($state) {
if ($instance->getActive() === $state) {
return $instance;
}
}, $this->collection);
}
}
Usage:
$instance = new Instance('eu');
$instance->turnOn();
$instance2 = new Instance('us');
$instance2->turnOff();
$collection = new InstanceCollection();
$collection->add($instance);
$collection->add($instance2);
echo $collection;
And output:
eu is switched on, us is switched off