public static function inWords($number)
{
$hyphen = '-';
$conjunction = ' and ';
$separator = ', ';
$negative = 'negative ';
$decimal = ' point ';
$dictionary = array(0 => 'zero', 1 => 'one', 2 => 'two', 3 => 'three', 4 => 'four', 5 => 'five', 6 => 'six', 7 => 'seven', 8 => 'eight', 9 => 'nine', 10 => 'ten', 11 => 'eleven', 12 => 'twelve', 13 => 'thirteen', 14 => 'fourteen', 15 => 'fifteen', 16 => 'sixteen', 17 => 'seventeen', 18 => 'eighteen', 19 => 'nineteen', 20 => 'twenty', 30 => 'thirty', 40 => 'fourty', 50 => 'fifty', 60 => 'sixty', 70 => 'seventy', 80 => 'eighty', 90 => 'ninety', 100 => 'hundred', 1000 => 'thousand', 1000000 => 'million', 1000000000 => 'billion', 1000000000000 => 'trillion', 1000000000000000 => 'quadrillion', 1000000000000000000 => 'quintillion');
if (!is_numeric($number)) {
return false;
}
if ($number >= 0 && (int) $number < 0 || (int) $number < 0 - PHP_INT_MAX) {
// overflow
trigger_error('convert_number_to_words only accepts numbers between -' . PHP_INT_MAX . ' and ' . PHP_INT_MAX, E_USER_WARNING);
return false;
}
if ($number < 0) {
return $negative . Helper::inWords(abs($number));
}
$string = $fraction = null;
if (strpos($number, '.') !== false) {
list($number, $fraction) = explode('.', $number);
}
switch (true) {
case $number < 21:
$string = $dictionary[$number];
break;
case $number < 100:
$tens = (int) ($number / 10) * 10;
$units = $number % 10;
$string = $dictionary[$tens];
if ($units) {
$string .= $hyphen . $dictionary[$units];
}
break;
case $number < 1000:
$hundreds = $number / 100;
$remainder = $number % 100;
$string = $dictionary[$hundreds] . ' ' . $dictionary[100];
if ($remainder) {
$string .= $conjunction . Helper::inWords($remainder);
}
break;
default:
$baseUnit = pow(1000, floor(log($number, 1000)));
$numBaseUnits = (int) ($number / $baseUnit);
$remainder = $number % $baseUnit;
$string = Helper::inWords($numBaseUnits) . ' ' . $dictionary[$baseUnit];
if ($remainder) {
$string .= $remainder < 100 ? $conjunction : $separator;
$string .= Helper::inWords($remainder);
}
break;
}
if (null !== $fraction && is_numeric($fraction)) {
$string .= $decimal;
$words = array();
foreach (str_split((string) $fraction) as $number) {
$words[] = $dictionary[$number];
}
$string .= implode(' ', $words);
}
return $string;
}