Array merge with same keys

Question

I have these three arrays:

Array
(
    [1] => [email protected]
    [2] => [email protected]
    [3] => [email protected]
)

Array
(
    [1] => 
    [2] => 4234235
    [3] => 
)

Array
(
    [2] => 1
)

And I want to generate this output:

Array
(
    [1] => array(
            [0] => [email protected]
            )
    [2] => array(
            [0] => [email protected]
            [1] => 4234235
            [2] => 1
            )
    [3] => array(
            [0] => [email protected]
            )
)

I need some assistance because I already researched array_merge_recursive() and array_merge(), but I can't get the correct result.

If I need to use foreach() what must I do to merge these 3 arrays.

Answer 1

Wrote a little script:

$a = array
(
    1=>"[email protected]",
    2=>"[email protected]",
    3=>"[email protected]",
);

$b = array
(
    2 => 4234235 
);

$c = array
(
    2 => 1
);

$arrayKeys = array_unique(
    array_merge(
        array_keys($a),
        array_keys($b),
        array_keys($c)
    )
);

$d = array_combine(
    $arrayKeys,
    array_fill(
        0,
        count($arrayKeys),
        array()
    )
);

foreach($a as $key => $value) {
    if(!empty($a[$key])) {
        $d[$key][] = $a[$key];
    }
    if(!empty($b[$key])) {
        $d[$key][] = $b[$key];
    }
    if(!empty($c[$key])) {
        $d[$key][] = $c[$key];
    }
}
var_dump($d);

Also if you want to you can merge together the arrays using the variable names only

//names of the variables to merge together
$arrayVariableNames = array("a","b","c");

//merging array keys together
$arrayKeys = array();
foreach($arrayVariableNames as $variableName) {
    $arrayKeys = array_merge(
        $arrayKeys,
        array_keys(${$variableName})
    );
}
$arrayKeys = array_unique($arrayKeys);

//initialize the result array with empty arrays
$resultArray = array_combine(
    $arrayKeys,
    array_fill(
        0,
        count($arrayKeys),
        array()
    )
);

//loop through all the keys and add the elements from all the arrays
foreach($resultArray as $key => &$value) {
    foreach($arrayVariableNames as $variableName) {
        if(!empty(${$variableName}[$key])) {
            $value[] = ${$variableName}[$key];
        }
    }
}