Used for simple algorithm attempts

If the sum of all factors of a positive integer greater than 1 is equal to itself, the number is called a perfect number. For example, 6 and 28 are both perfect numbers: 6=1+2+3; 28=1+2+4+ 7+14.

//Judge whether it is a complete number
 function is_factor($factor)
 {
 if($factor<1) return false;
 if($factor==1) return array(1);
 if(! isset($arr)){$arr=array();}
 for($i=1;$i<$factor;$i++){
 if($factor%$i==0){
 $arr[ ]=$i;
 }
 }
 $len=count($arr);
 $i=0;$temp=0;
 while($i<$len) {$temp+=$arr[$i]; $i++;}
 if($temp==$factor) return $arr;
 else return false;
 }
 $factor=6;
 $count=0;

 for($i=1;$i<= $factor;$i++)
 {
 $res=is_factor($i);
 $len=count($res);
 if(is_array($res)){
 echo $i.'=';
 for( $j=0;$j<$len;$j++){
 if($j!=0) echo '+'.$res[$j];
 else echo $res[$j];
 }
 $ count++;
 echo '';
 }
 }
 if($count==0) echo 'No complete number!';