Windows Batch File - ENABLEDELAYEDEXPANSION query

Question

Having read an existing post on stackoverflow and done some reading around on the net. I thought it was time to post my question before I lost too much hair!

I have the following code within a batch file which I double click to run, under Windows XP SP3:

SETLOCAL ENABLEDELAYEDEXPANSION

::Observe variable is not defined
SET test

::Define initial value
SET test = "Two"

::Observe initial value is set
SET test

::Verify if the contents of the variable matches our condition
If "!test!" == "Two" GOTO TWO

::First Place holder
:ONE

::Echo first response
ECHO "One"

::Second Place holder
:TWO

::Echo second response
ECHO "Two"

::Await user input
PAUSE

ENDLOCAL

Basically I am trying to establish if I can navigate through my script using conditionals. It seems apparent that I am getting some issues with variable scope and delayed variable expansion yet I'm a little lost on what I'm doing wrong.

Can anyone point me in the right direction?

Answer 1

Your immediate problem is that you're setting the variable to the value < "Two"> which you can see here:

@echo off

SETLOCAL ENABLEDELAYEDEXPANSION

::Observe variable is not defined
SET test

::Define initial value
SET test = "Two"

::Observe initial value is set
SET test
echo %test%
echo..%test %.

::Verify if the contents of the variable matches our condition
If "!test!" == "Two" GOTO TWO

::First Place holder
:ONE

::Echo first response
ECHO "One"

::Second Place holder
:TWO

::Echo second response
ECHO "Two"

::Await user input
PAUSE

ENDLOCAL

which produces:

Environment variable test not defined
test = "Two"
. "Two".
"One"
"Two"
Press any key to continue . . .

The reason your "set test" is outputting the variable is the same reason why "set t" would - if there's no variable of the specific name, it outputs all variables starting with that name.

The set command is also a finicky little beast and does not like spaces surrounding the '=' characters; it incorporates them (and the quotes by the way) into the environment variable name and the value assigned to it. Instead, use:

set test=Two

Also, where you're using delayed expansion, it doesn't matter since %test% and !test! would expand the same. It's useful in statements like:

if "!test!" == "Two" (
    set test=TwoAndABit
    echo !test!
)

The inner echo will output TwoAndABit whereas %test%, which is expanded when the whole if-statement is encountered, would cause it to output Two.

Still, I always use delayed expansion everywhere just for consistency.

Answer 2

The SET command takes everything after the equal sign through the last non-blank character. Your command...

SET test = "Two"

...is setting the variable test to the value "Two" with a leading blank and the quotes, not just the string Two.

So when you test ...

If "!test!" == "Two" GOTO TWO

you are really testing...

If " "Two"" == "Two" GOTO TWO