Windows Batch Variables Won't Set

Question

I think I ran into a bug in Window\'s batch scripting.

I cannot set variables that are in an expanded if statement.

Here is an isolated part of my script:

Answer 1

Just a remind, the ms-dos "set" command takes every string after the equal sign. So if you write

if "x"=="x" set a=foo else set a=bar
echo %a%  // output : foo else set a=bar

The %a% is actually set to "foo else set a=bar", not foo. So I always use "()" for set command if there are multiple commands in one line.

if "%1"=="" (set a=20) else (set a=%1)