php string to float

str_to_float

$str_rate = $this->settings['zones_form_'.$i.'_fee'];
$final_rate = (float)$str_rate;

$debug_arr = array(
  '$str_rate' => $str_rate,
  '$str_rate type' => gettype($str_rate),
  '$final_rate' => $final_rate,
  '$final_rate type' => gettype($final_rate),
);
print_r($debug_arr);


/*** RESULT
Array (
  [$str_rate] => ​4.99
  [$str_rate type] => string
  [$final_rate] => 0
  [$final_rate type] => double
) 
***/