PHP - for循环如何使用$ i + 1

Question

Hello I'm writing PHP upload multiple files and I want to add ordinal number suffix to the filename.

but my for loop start from $i = 0(because of array) so I want to add suffix filename from 1 not zero by use $i + 1 on the line : $newname = "id".$id."_".date('Y-m-d')."_".$i+1.".".$file_extension; but It's get syntax error

here is my code.

$count = count($_FILES["images"]["name"]);
$arr_newname = array();
for($i=0; $i <= $count; $i++){   
              if ((($_FILES["images"]["type"][$i] == "image/gif")
             || ($_FILES["images"]["type"][$i]  == "image/jpeg")
            || ($_FILES["images"]["type"][$i]  == "image/png")
            || ($_FILES["images"]["type"][$i] == ""))
            && ($_FILES["images"]["size"][$i] < 9000000)) //9 MB
            {

                $split = explode(".", $_FILES["images"]["name"][$i]);
                $file_extension = end($split);

                $newname = "id".$id."_".date('Y-m-d')."_".$i+1.".".$file_extension; 
                $arr_newname[$i] = $newname;
                move_uploaded_file($_FILES["images"]["tmp_name"][$i] , "images/location/".$newname);

              }
              else{
              echo "Invalid file;
              } 
            }

for now, I solve problem by use for loop start from $i=1 and use $i-1 on array instead. but it's very ugly code for me.

for($i=1; $i <= $count; $i++){   
   if ((($_FILES["images"]["type"][$i-1] == "image/gif")
             || ($_FILES["images"]["type"][$i-1]  == "image/jpeg")
            || ($_FILES["images"]["type"][$i-1]  == "image/png")
            || ($_FILES["images"]["type"][$i-1] == ""))
            && ($_FILES["images"]["size"][$i-1] < 9000000)) //9 MB 
            {

                $split = explode(".", $_FILES["images"]["name"][$i-1]);
                $file_extension = end($split);

                $newname = "id".$id."_".date('Y-m-d')."_".$i.".".$file_extension; 
                $arr_newname[$i-1] = $newname;
                move_uploaded_file($_FILES["images"]["tmp_name"][$i-1] , "images/location/".$newname);

              }
              else{
              echo "Invalid file;
              } 
            }

So Is there other way to I use $i+1 on the $newname file? and why $i-1 work fine on those array

Answer 1

($i+1) dude.

$newname = "id".$id."_".date('Y-m-d')."_".($i+1).".".$file_extension;