Shell script to find the total size of the files given as positional parameters using function

PROGRAM
#size function to find the total size of the files
size()
{
  s=0
  for i in $*
  do
    if test -f $i
    then
       sz=`ls -l $i|tr -s " "|cut -d " " -f5`
       s=`expr $s + $sz`
    else
       echo $i is not a file
    fi
  done
  return $s
}
size $*
ret=$?
echo "Total size is " $s


OUTPUT
sh sizFunc.sh fibt file fil2
fil2 is not a file
Total size is  159