PHP: find key in nested associtive array

Question

I have a method to check whether a key is in a nested associative array:

private function checkKeyIsInArray($dataItemName, $array) {      
    foreach ($array as $key=>$value) {
        if ($key == $dataItemName) return true;
        if (is_array($value)) {
            checkKeyIsInArray($dataItemName, $value);
        }
    }
    return false;
}

It always returns true, regardless of the keys I include or do not include. Here is my test array:

Array
(
[0] => Array ( [reset_time] => 2013-12-11 22:24:25 )
[1] => Array ( [email] => [email protected] )
)

Please, what am I doing wrong? If I search for "reset_time" the method returns true (as I expect); when I search for "reset_expired" the method also returns true (which is incorrect).

sectus · Accepted Answer · 2013-12-12 05:16:31Z

1

Your method is almost works. But there is few issues.

Comparsion numeric values and strings. In first round method has 0 as key and 'email' as value. 0 == 'email' always returns true.
You should use $this when calling object member function.
You should return value of recursive function.

Your rewrited method.

class check
    {

    private function checkKeyIsInArray($dataItemName, $array)
        {
        foreach ($array as $key => $value)
            {
            // convert $key to string to prevent key type convertion
            if ((string) $key == $dataItemName)
                return true;
            if (is_array($value))
            // $this added
            // return added
                return $this->checkKeyIsInArray($dataItemName, $value);
            }
        return false;
        }

    public function myCheck($dataItemName, $array)
        {
        return $this->checkKeyIsInArray($dataItemName, $array);
        }

    }

$check = new check();
$array = array(array('reset_time' => 123, 'email' => 123));
var_dump($check->myCheck('reset_time', $array)); // true
var_dump($check->myCheck('reset_expired', $array)); // false
var_dump($check->myCheck('0', $array)); // true

edited Dec 12, 2013 at 5:16

answered Dec 12, 2013 at 0:51

sectus

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1 Comment

Steve Cooke Over a year ago

Thank you Sectus - this looks correct. I will add the suggested alterations later this afternoon and test, but just reading your code makes sense to me.

praveen · Accepted Answer · 2013-12-12 05:36:51Z

1

I have updated your own code, there was some minor issue.please check.

function checkKeyIsInArray($dataItemName, $array) {      
   foreach ($array as $key=>$value) {
    ## here $key is int and $dataItemName is string so its alway comes true in ur case
    if ("$key" == $dataItemName) {
         return true;
    }
    else if (is_array($value)) {
        $returnvalue=checkKeyIsInArray($dataItemName, $value);
        ## once a matching key found  stop further recursive call
        if($returnvalue==true){
          return true;
        }
    }
  }
   return false;
}

answered Dec 12, 2013 at 5:36

praveen

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1 Comment

Steve Cooke Over a year ago

Thank you for your input Praveen. Your solution is similar to the one suggested by Sectus.

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