在结果之间添加空格[关闭]

I have the following code and output

for ($i=0;$i<=100;$i++)
if ($i % 2!=0)
echo $i + "";


?>

13579111315171921232527293133353739414345474951535557596163656769717375777981838587899193959799 The problem is that there is no space between the numbers. How do I add this space

Change echo $i + ""; to echo $i . " ";

for ($i=0;$i<=100;$i++)
  if ($i % 2!=0)
      echo "$i ";