How to check if element is in a Nested Array PHP?

Question

USE CASE :

$a = [1, 2, [3, 4, 5], [6, [7, 8], 8, 10]];
isNumberPresentInArray($a, 10) // returns true;
isNumberPresentInArray($a, 2) // returns true;
isNumberPresentInArray($a, 14) // returns false;

I would like to check if there element exist in array.The following is my version of code. but its not working perfectly for inner arrays. Please help me.

$a = [1, 2, [3, 4, 5], [6, [7, 8], 8, 10]];

function isNumberPresentInArray($a, $b) {
    foreach($a as $v)
    {
        if (is_array($v)) {
            return isNumberPresentInArray($v, $b);
        } else {
            if ($v == $b) {
                return true;
            }
        }
    }
}

echo isNumberPresentInArray($a, 1);

Syscall · Accepted Answer · 2022-01-27 08:13:39Z

Your error is here :

return isNumberPresentInArray($v, $b);

You should return the result of the function only if the result is true, because, if you don't do that, you will stop the loop and don't check values after this point. You also missed the return false and get NULL instead of false if $b was not found.

function isNumberPresentInArray($a, $b) 
{
    foreach($a as $v)
    {
        if (is_array($v)) {
            if (isNumberPresentInArray($v, $b)) {
                return true;
            }
        } 
        elseif ($v == $b) {
            return true;
        }
    }
    return false;
}

Usage

$a = [1, 2, [3, 4, 5], [6, [7, 8], 8, 10]];
var_dump(isNumberPresentInArray($a, 10)); // bool(true);
var_dump(isNumberPresentInArray($a, 2)); // bool(true);
var_dump(isNumberPresentInArray($a, 14)); // bool(false);
var_dump(isNumberPresentInArray($a, 1)); // bool(true);

See also a live demo (3v4l.org).

lukas.j · Accepted Answer · 2022-01-27 10:52:07Z

1

You could use an iterator:

$arr = [ 1, 2, [ 3, 4, 5 ], [ 6, [ 7, 8 ], 9, 10 ] ];

function isNumberPresentInArray(array $arr, int $number): bool {
  $it = new RecursiveIteratorIterator(new RecursiveArrayIterator($arr), RecursiveIteratorIterator::LEAVES_ONLY);
  foreach ($it as $value) {
    if ($value === $number) {
      return true;
    }
  }
  return false;
}

echo '10: ' . ( isNumberPresentInArray($arr, 10) ? 'yes' : 'no' ) . "\n";
echo ' 2: ' . ( isNumberPresentInArray($arr, 2) ? 'yes' : 'no' ) . "\n";
echo '14: ' . ( isNumberPresentInArray($arr, 14) ? 'yes' : 'no' ) . "\n";

This will print:

10: yes
 2: yes
14: no

edited Jan 27, 2022 at 10:52

answered Jan 27, 2022 at 10:46

lukas.j

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