How can check multiple values in array in php?

If you're looking to optimize this search with just a comparison check only I would do:

public function items_in_array($needles, $haystack)
{
    foreach ($needles as $needle) {
        if (!in_array($needle, $haystack)) {
            return false;
        }
    }

    return true;
}

if you're willing to do it ugly doing multiple if(in_array(...&&in_array(... is even faster.

I did a test with 100 and another with 100,000 array elements and between 2 and 15 needles using array_intersect, array_diff, and in_array.

in_array was always significantly faster even when I had to do it 15x for different needles. array_diff was also quite a bit faster than array_intersect.

So if you're just trying to search for a couple of things to see if they exist in an array in_array() is best performance-wise. If you need to know the actual differences/matches then it's probably just easier to use array_diff/array_intersect.

Feel free to let me know if I did my calculations wrong in the ugly example below.

true0
";
}

$total_time = microtime(true) - $start_time;
echo "
";
echo($total_time);



$start_time = microtime(true);

if (
    in_array($n1, $arr) !== false &&
    in_array($n2, $arr) !== false &&
    in_array($n3, $arr) !== false &&
    in_array($n4, $arr) !== false &&
    in_array($n5, $arr) !== false &&
    in_array($n6, $arr) !== false &&
    in_array($n7, $arr) !== false &&
    in_array($n8, $arr) !== false &&
    in_array($n9, $arr) !== false &&
    in_array($n10, $arr) !== false &&
    in_array($n11, $arr) !== false &&
    in_array($n12, $arr) !== false &&
    in_array($n13, $arr) !== false &&
    in_array($n14, $arr) !== false &&
    in_array($n15, $arr)!== false) {
    echo "
true1
";
}

$total_time = microtime(true) - $start_time;
echo "
";
echo($total_time);

$first_time = $total_time;

echo "
";

$start_time = microtime(true);

if (empty($diff = array_diff($narr,$arr)))
{

    echo "
true2
";
}


$total_time = microtime(true) - $start_time;
echo($total_time);
print_r($diff);
echo "
";

echo "
";
if ($first_time > $total_time)
{
    echo "First time was slower";
}

if ($first_time < $total_time)
{
    echo "First time was faster";
}

echo "
";


$start_time = microtime(true);

if (count(($itrs = array_intersect($narr,$arr))) == count($narr))
{

    echo "
true3
";
    print_r($result);
}


$total_time = microtime(true) - $start_time;
echo "
";
echo($total_time);

print_r($itrs);

echo "
";

if ($first_time < $total_time)
{
    echo "First time was faster";
}


echo "
";
print_r($narr);
echo "
";
print_r($arr);

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I want to see if one of two values (a, b) are in an array. Here's my current thought:

$match_array = array('a','b');
$array_under_test = array('b', 'd', 'f');

if (array_intersect($match_array, $array_under_test)) {
  // Success!
}

Any better implementations?

asked Apr 19, 2013 at 21:42

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If you want to verify that either value is in the $array_under_test, array_intersect may not be the best option. It will continue to test for collisions even after it finds a match.

For two search strings you can just do:

if (in_array('a', $array_under_test) || in_array('b', $array_under_test)) {
  // Success!
}

This will stop searching if 'a' is found in the $array_under_test.

For more than two values, you can use a loop:

foreach ($match_array as $value) {
  if (in_array($value, $array_under_test)) {
    // Success!
    break;
  }
}

answered Apr 19, 2013 at 22:26

p.s.w.gp.s.w.g

1,9512 gold badges15 silver badges29 bronze badges

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0

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In addition to p.w.s.g's answer (which seems fine):

If you have lots of values you need to find, you can use a hash:

// the values go into keys of the array
$needles = array('value1' => 1, 'value2' => 1, 'value3' => 1);
$haystack = array('test', 'value1', 'etc');

// only go through the array once
$found = false;
foreach($haystack as $data) {
   if (isset($needles[$data])) {
       $found = true; break;
   }
 }

It's worth doing this if you search $haystack a lot of times.

answered Apr 21, 2013 at 6:09

cobrucobru

961 silver badge2 bronze badges

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