title: Missing Operator when using set /a
body: <p>So I am creating a Batch Operating System, but the problem is... IT KEEPS SAYING MISSING OPERATOR!!</p>
  
  <p>Here is a snippet of my code:</p>
  
  <pre><code>@echo off
  
   title LiME - Version 1.0 
   mode con: cols=86 lines=21
  
   if exist "\SystemLiME" goto startup.jsc
  
     ) else (
  
   if not exist "\SystemLiME" goto boot.jfk
  
  
   :boot.jfk
  
  cls
  
  echo                                         MAINBOOTCONFIG                                        
  
  echo.
  
  echo CHECKING FOR VOLUMES TO CREATE..
  
  ping localhost -n 5 &gt;nul
  
   if exist "\SystemLiME" set create-vol1=0
  
    ) else (
  
   if not exist "\SystemLiME" set create-vol1=1
  
   if exist "\SystemLiME\pkgs" set create-vol2=0
  
    ) else (
  
   if not exist "SystemLiME\pkgs" set create-vol2=1
  
   if %create-vol1% == 0 set /a count-vol-create=0
   if not %create-vol1% == 0 set /a count-vol-create=%count-vol-create%+=1
  
   if %create-vol2% == 0 set /a count-vol-create=%count-vol-create%+=0
   if not %create-vol2% == 0 set /a count-vol-create=%count-vol-create%+=1
  
   echo %count-vol-create%
   pause
  </code></pre>
  
  <p>But what I'm focusing on is this:</p>
  
  <pre><code>:boot.jfk
  
   cls
  
   echo                                         MAINBOOTCONFIG                                        
  
   echo.
  
   echo CHECKING FOR VOLUMES TO CREATE..
   ping localhost -n 5 &gt;nul
  
   if exist "\SystemLiME" set create-vol1=0
  
    ) else (
  
   if not exist "\SystemLiME" set create-vol1=1
  
   if exist "\SystemLiME\pkgs" set create-vol2=0
  
    ) else (
  
   if not exist "SystemLiME\pkgs" set create-vol2=1
  
   if %create-vol1% == 0 set /a count-vol-create=0
   if not %create-vol1% == 0 set /a count-vol-create=%count-vol-create%+=1
  
   if %create-vol2% == 0 set /a count-vol-create=%count-vol-create%+=0
   if not %create-vol2% == 0 set /a count-vol-create=%count-vol-create%+=1
  
   echo %count-vol-create%
   pause
  </code></pre>
  
  <p>Everytime I start this code, I get 'Missing operator.'
                                     'Missing operator.'
                                     'ECHO is off.'
                                     'Press any key to continue...'</p>
  
  <p>please help me!! :'(  (btw, im new to stackoverflow :) )</p>