Compare Two Associative Array with different value

Question

I have two Associative array.

$a1 = array("Peter"=>"a","Ben"=>"b","Joe"=>"c");
$a2 = array("Peter"=>"5","Joe"=>"15");

and Out put result should be...

a=5
b=null
c=15

Answer 1

foreach($a1 as $aKey => $aValue) {
    echo $aValue, '=';
    echo (isset($a2[$aKey])) ? $a2[$aKey] : 'null';
    echo PHP_EOL;
}

Answer 2

foreach($a1 as $key => $value) {
    echo $a1[$key].'='.$a2[$key];
}

You will get the output, but this have nothing to do with array comparing.