Difficulty checking if elements in array are type integer PHP

I am trying to detect if one or more variables contain numbers. I have tried a few different methods, but I have not been entirely successful.

Here is what I have tried.

<?php
$one = '1';
$two = '2';

$a1 = '3';
$a2 = '4';
$a3 = '5';


$string_detecting_array = array(); 

array_push($string_detecting_array, $one,$two,$a1,$a2,$a3); 

foreach ($string_detecting_array as $key) { 
    if (is_numeric($key)) {
        echo 'Yes all elements in array are type integer.';
    } 
    else {
        echo "Not all elements in array were type integer.";
    }
}

?>

I haven't been successful using this method. Any ideas? Thankyou in advance!

You can use gettype if you want to explicitly know if the variable is a number. Using is_numeric will not respect types.

If you are intending to use is_numeric but want to know if all elements are, then proceed as follows:

$all_numeric = true;
foreach ($string_detecting_array as $key) { 
    if (!(is_numeric($key))) {
        $all_numeric = false;
        break;
    } 
}

if ($all_numeric) {
    echo 'Yes all elements in array are type integer.';
} 
else {
    echo "Not all elements in array were type integer.";
}