Batch file fails to set environment variable within conditional statement

Question

Why does the following Windows Batch File output Foo followedby Bar, rather than Baz?

@echo off
setlocal

set _=Foo
echo %         


        

Answer 1

The answer to this is the same as the answer to:Weird scope issue in batch file. See there for more details. Basically variable expansion is done at line read time, not at execution time.