number in words

<?php
function spellNumberInEnglish ($number) {
$number = strval($number);
if (!ereg("^[0-9]{1,15}$", $number))
return(false);
$ones = array("", "one", "two", "three", "four",
"five", "six", "seven", "eight", "nine");
$teens = array("ten", "eleven", "twelve", "thirteen", "fourteen",
"fifteen", "sixteen", "seventeen", "eighteen", "nineteen");
$tens = array("", "", "twenty", "thirty", "forty",
"fifty", "sixty", "seventy", "eighty", "ninety");
$majorUnits = array("", "thousand", "million", "billion", "trillion");
$result = "";
$isAnyMajorUnit = false;
$length = strlen($number);
for ($i = 0, $pos = $length - 1; $i < $length; $i++, $pos--) {
if ($number{$i} != '0') {
if ($pos % 3 == 0)
$result .= $ones[$number{$i}] . ' ';
else if ($pos % 3 == 1) {
if ($number{$i} == '1') {
$result .= $teens[$number{$i + 1}] . ' ';
$i++; $pos--;
} else {
$result .= $tens[$number{$i}];
$result .= $number{$i + 1} == '0'? ' ' : '-';
}
} else
$result .= $ones[$number{$i}] . " hundred ";
$isAnyMajorUnit = true;
}
if ($pos % 3 == 0 && $isAnyMajorUnit) {
$result .= $majorUnits[$pos / 3] . ' ';
$isAnyMajorUnit = false;
}
}
trim($result);
if ($result == "") $result = "zero";
return($result);
}

echo spellNumberInEnglish('100');
?>