PHP number to Chinese character code (algorithm)_PHP tutorial

//Convert numbers to Chinese characters, such as 1210 to one thousand two hundred and ten
$num = "842105580";//Nine-digit number
function del0($num) //Remove the 0 in front of the number field
{
return "".intval($num);
}
function n2c($x) //A single number changes to a Chinese character
{
$arr_n = array("zero","one","two","three","four","five" ,"six","seven","eight","nine","ten");
return $arr_n[$x];
}
function num_r($abcd) //Read Value (4 digits)
{
$arr= array();
$str = ""; //The read Chinese character value
$flag = 0; //Whether the bit is Zero
$flag_end = 1; //Whether it ends with "zero"
$size_r = strlen($abcd);
for($i=0; $i<$size_r; $i++)
{
$arr[$i] = $abcd{$i};
}
$arrlen = count($arr);
for($j=0; $j<$arrlen ; $j++)
{
$ch = n2c($arr[$arrlen-1-$j]); //Convert Chinese characters from back to front
echo $ch;
echo "" ;
if($ch == "zero" && $flag == 0){ //If it is the first zero
$flag = 1; //This bit is zero
$str = $ ch.$str; //Add Chinese character numerical string
continue;
}elseif($ch == "zero"){ //If it is not the first zero
continue;
}
$flag = 0; //This bit is not zero
switch($j) {
case 0: $str = $ch; $flag_end = 0; break; //The first bit (last) , does not end with "zero"
case 1: $str = $ch."十".$str; break; //The second digit
case 2: $str = $ch."hundred".$ str; break; //The third digit
case 3: $str = $ch."千".$str; break; //The fourth digit
}
}
if($flag_end == 1) //If it ends with "zero"
{
mb_internal_encoding("UTF-8");
$str = mb_substr($str, 0, mb_strlen($str)-1); //Remove "zero"
}
return $str;
}
function num2ch($num) //Overall read conversion
{
$num_real = del0($ num);//Remove the leading "0"
$numlen = strlen($num_real);
echo "numlen=".$numlen."";
if($numlen >= 9) //If it reaches nine digits, read the "billion" digits
{
$y=substr($num_real, -9, 1);
//echo $y;
$wsbq = substr ($num_real, -8, 4);
$gsbq = substr($num_real, -4);
$a = num_r(del0($gsbq));
$b = num_r(del0( $wsbq))."Million";
$c = num_r(del0($y))."Billion";
}elseif($numlen <= 8 && $numlen >= 5) // If greater than or equal to "ten thousand"
{
$wsbq = substr($num_real, 0, $numlen-4);
$gsbq = substr($num_real, -4);
$a = num_r(del0($gsbq));
$b = num_r(del0($wsbq))."万";
$c="";
}elseif($numlen <= 4) //If less than or equal to "thousand"
{
$gsbq = substr( $num_real, -$numlen);
$a = num_r(del0($gsbq));
$b=" ";
$c="";
}
$ch_num = $c.$b.$a;
return $ch_num;
}
echo $num."" ; //Number
echo num2ch($num); //Chinese characters
echo "";
echo num2ch("1240");