How to do equality check of array values and keys from another array?

Question

I have two diff array and I want to print these array based on equal condition.

First array

     Array ( 
            [0] => fname 
            [1] => lname 
            [2] => email  
      )

Second array

   Array ( 
           [fname] => john 
           [lname] => notdefined 
           [email] => [email protected] 
           [address] => london 
    )

Now my problem is I want to print values from second array if and only if this array's index match with first array values...

Second array's index == first array's value (I can say this is equality condition for better understanding)

In this case my output should be

   Array (
           [fname] => john
           [lname] => notdefined
           [email] => [email protected]
      )

It should not display address because in first array is not present...

Here this is just sample code but in reality I have a very big array with some additional info also.

Flip your first array with array_flip and then make use of array_intersect_key on the two arrays. — Shankar Narayana Damodaran
– Shankar Narayana Damodaran, Commented Feb 10, 2014 at 9:37
@ShankarDamodaran your suggestion worked like charm bro... thanks a lot — Kalpit
– Kalpit, Commented Feb 10, 2014 at 9:49

Dharman · Accepted Answer · 2021-09-26 13:39:47Z

1

There are plenty of ways, one of them is:

foreach($secArr as $key => $val)
{
     if(in_array($key, $firstArr))
         echo $val;
}

or:

$keys = array_flip($firstArr);
$arr = array_intersect_key($secArr, $keys);
//display $arr;

or:

foreach($firstArr as $key)
{
     if($secArr[$key])
         echo $secArr[$key];
}

edited Sep 26, 2021 at 13:39

answered Feb 10, 2014 at 9:40

Dharman♦

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1 Comment

Kalpit Over a year ago

worked like charm with foreach ways.. need to test array_flip

Dharman · Accepted Answer · 2021-09-26 13:38:19Z

1

Swap first array key and value using array_flip function and Computes the intersection of arrays using keys for comparison using array_intersect_key.

$array1 = array(0 => 'fname',1 => 'lname' ,2 => 'email');
$array1 = array_flip($array1);
$array2 = array( 
       'fname' => 'john', 
       'lname' => 'notdefined', 
       'email' => '[email protected]', 
       'address' => 'london' 
    );

$new = array_intersect_key($array2,$array1);
print_r($new);

working demo

edited Sep 26, 2021 at 13:38

Dharman♦

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answered Feb 10, 2014 at 9:46

Roopendra

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