Question

For instance, “000”, “404”, and “0523” can be converted into whole numbers in PHP, but “42sW” and “423 2343” cannot be converted into whole numbers.

Answer 1

Use the ctype_digit function. is_numeric will also permit floating point values.

$numArray = array("1.23","156", "143", "1w");
foreach($numArray as $num)
{
    if (ctype_digit($num)) {
            // Your Convert logic
        } else {
            // Do not convert print error message
        }
    }
}