Question

How to apply callback function to each element of an array in PHP

Answer 1

function power2($n)
{
    return $n * $n;
}

$arr = array(1, 2, 3, 4, 5, 6, 7);
$arr_power2 = array_map("power2", $arr);

print_r($arr_power2);

/*
run:
 
Array ( [0] => 1 [1] => 4 [2] => 9 [3] => 16 [4] => 25 [5] => 36 [6] => 49 ) 
 
*/

 

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Answer 2

function power3($n)
{
    return $n * $n * $n;
}

$arr = array(1, 2, 3, 4, 5, 6, 7);
$arr_power3 = array_map("power3", $arr);

print_r($arr_power3);

/*
run:
 
Array ( [0] => 1 [1] => 8 [2] => 27 [3] => 64 [4] => 125 [5] => 216 [6] => 343 ) 
 
*/

 

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Answer 3

$numbers = array(1, 2, 3, 4);
$words = array("one", "two", "three", "four");
$numbers_words = array_map(null, $numbers, $words);

echo "<pre>";
print_r($numbers_words);
echo "</pre>";

/*
run:
 
Array
(
    [0] => Array
        (
            [0] => 1
            [1] => one
        )

    [1] => Array
        (
            [0] => 2
            [1] => two
        )

    [2] => Array
        (
            [0] => 3
            [1] => three
        )

    [3] => Array
        (
            [0] => 4
            [1] => four
        )

)
 
*/

 

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