title: How to split strings by in loop of batch
body: <p>Generally, i want do do some operations to some vars in a loop, the number of vars may change, i tried a sample like this:</p>
  
  <p>set header1=appdef1.h<br>
  set header2=appdef2.h<br>
  set header3=appdef3.h<br>
  set headers= "%header1% %header2% %header3%"<br>
  for /f "delims= " %%i in (%headers%) do echo %%i<br>
  pause</p>
  
  <p>while it only output "appdef.h", confusing!</p>