Batch different way to access array

Question

This is my script:

@echo off
setlocal EnableDelayedExpansion
set "memuc=d:\file.exe"

set array[0]=foo
set array[1]=bar

set x=0


:SymLoop
if defined array[!x!] (
    call "!memuc!" start -n !!array[%x%]!!

    set /A x=!x! + 1
    GOTO :SymLoop
)

endlocal

Why array[!x!] line cannot be replaced with with !array[%x%]!? I thought I have to use ! when accesing delayedExpansion variables.
Why I have to use %x% instead !x!?. The same, I thought ! should be necessary accesing x variable
Why I have to use two ! here !!array[%x%]!!?

tukan · Accepted Answer · 2019-09-27 13:41:33Z

I think you got the concept wrong. The ! means that the value of the variable will be expanded as late as possible.

@echo off
SETLOCAL EnableDelayedExpansion
set "_var=stackoverflow"
set "_var=rules" & echo "%_var% !_var!"

This will print "stackoverflow rules" due to the fact of the delayed expansion.

Now to your questions:

Addum 1. The reason is the if defined. If you would like to put there the actual variable you would use e.g. your array[0] that is the reason why you have array[!x!] and not !array[%x%]!.

Addum 2. You have to use %x% to have immediate expansion as you want to have array[0] and array[1]. If you would write it as !x! then you would be searching, if written as %array[!x!]% for array[!x!].

Addum 3. The double exclamation marks (!!) is there due to the fact that call introduces one more expansion. So first you have immediate expansion of %x% then you have an expansion of array[0] and then expansion for the call.

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