A function to convert Arabic numerals to Chinese numerals_PHP tutorial

Recently, due to need, I wrote a "function to convert Arabic numerals to Chinese numerals". I searched the highlights section and found only one similar one.
I feel that my algorithm is good, so I posted it to share it. If it is to be used for the conversion of amounts, the processing of the decimal part needs to be modified
function ch_num($num,$mode =true) {
$char = array("zero","一","二","三","四","五","鲁","七","八","九" ");
$dw = array("","十","䰰","千","","万","千亿"," trillion");
$dec = "point ";
$retval = "";

if($mode)
preg_match_all("/^0*(d*).?(d*)/",$num, $ar );
else
preg_match_all("/(d*).?(d*)/",$num, $ar);

if($ar[2][0] ! = "")
$retval = $dec . ch_num($ar[2][0],false); //If there are decimals, process the decimals recursively first
if($ar[1][0] != "") {
$str = strrev($ar[1][0]);
for($i=0;$i $out[$i] = $char[$str[$i]];
if($mode) {
$out[$i] .= $str[$i] != "0"? $dw[$i%4] : "";
If($str[$i]+$str[$i-1] == 0)
$out[$i] = "";
if($i%4 == 0)
$out[$i] .= $dw[4+floor($i/4)];
}
}
$retval = join("",array_reverse($out)) . $retval;
}
return $retval;
}

//echo ch_num("12345006789001.123");
//echo ch_num("880079.1234");
echo ch_num("300045.0123");

?>