Windows Batch Script: enable delayed expansion

In compound code blocks, with setting EnableDelayedExpansion, the current value will NOT assigned to the variable as expected. see the code below:

set var=1
set switch=on

if "%switch%"=="on" (
   set var=2
   echo %var%
   REM it prints 1
)

It actually prints the original value 1. To avoid such unexpected behaviour, you need to set EnableDelayedExpansion, and using !var!:

setlocal EnableDelayedExpansion
set var=1
set switch=on

if "%switch%"=="on" (
   set var=2
   echo !var!
   REM it prints 2
)

see also

• EnableDelayedExpansion
• Why does this batch variable never change even when set?
• Enable and Disable Delayed Expansion, what does it do?