PHP implements RMB digital formatting, adding commas to every three digits

function num_format($num){
 if(!is_numeric($num)){
 return false;
 }
 $rvalue='';
 $num = explode('.',$num);/ /Separate integers and decimals
 $rl = !isset($num['1']) ? '' : $num['1'];//The value of the decimal part
 $j = strlen($num[0] ) % 3;//How many digits are there in the integer
 $sl = substr($num[0], 0, $j);//Get the number with less than three digits in front of it
 $sr = substr($num[0], $j);//Take out the following three-digit number
 $i = 0;
 while($i <= strlen($sr)){
 $rvalue = $rvalue.','.substr($ sr, $i, 3);//Take out the three digits and combine them, separated by commas
 $i = $i + 3;
 }
 $rvalue = $sl.$rvalue;
 $rvalue = substr($ rvalue,0,strlen($rvalue)-1);//Remove the last comma
 $rvalue = explode(',',$rvalue);//Decompose into an array
 if($rvalue[0]==0) {
 array_shift($rvalue);//If the first element is 0, delete the first element
 }
 $rv = $rvalue[0];//The number with less than three digits in front
 for($i = 1 ; $i < count($rvalue); $i++){
 $rv = $rv.','.$rvalue[$i];
 }
 if(!empty($rl)){
 $rvalue = $rv.'.'.$rl;//The decimal is not empty, integers and decimals are combined
 }else{
 $rvalue = $rv;//The decimal is empty, only integers
 }
 return $rvalue;
}

PHP