How to extract numbers from a string in PHP?

Regular expressions can be used to extract numbers from a string, for example using the preg_match_all function to match all numbers.

$str = "Hello123World456";
preg_match_all('/\d+/', $str, $matches);
$numbers = $matches[0];

print_r($numbers);

output result:

Array
(
    [0] => 123
    [1] => 456
)

In the code above, the regular expression /\d+/ is used to match consecutive numbers, and then the preg_match_all function is used to save all the matching results in the $matches variable. Finally, the extracted numbers are printed out.