Reference element by index in a list using Batch Script - windows

Question

Trying to obtain an element in a list by its index, using batch script. Here is the code:
#Echo off
setlocal EnableDelayedExpansion
set acc[0]=default
set acc[1]=Account_2
set acc[2]=Account_3
set acc[3]=Account_4
set acc[4]=Account_5
if exist interator.txt (
set /p i=<interator.txt
echo "read: !i!"
echo "!acc[%i%]!"
REM start cmd /c setx AWS_PROFILE !acc[%i%]!
REM start cmd /k python script.py
set /A i=i+1
(echo !i!)>interator.txt
echo "write: !i!"
) else (
(echo 0)>interator.txt
)
Output Received:
"read: 0"
""
"write: 1"
As setx requires the CMD session to be closed, for affect to take place. I am trying a different approach to automate some regular stuff.
Expected Output:
"read: 0"
"default"
"write: 1"

Answer 1

#Echo off
setlocal EnableDelayedExpansion
set "acc[0]=default
set "acc[1]=Account_2"
set "acc[2]=Account_3"
set "acc[3]=Account_4"
set "acc[4]=Account_5"
if exist q65771965.txt (
set /p i=<q65771965.txt
echo "read: !i!"
FOR %%a IN (acc[!i!]) DO (
ECHO "!%%a!"
echo start cmd /c setx AWS_PROFILE "!%%a!"
echo start cmd /k python script.py
)
set /A i=i+1
(echo !i!)
echo "write: !i!"
) else (
(echo 0)
)
GOTO :EOF
OK - small changes to allow this to work on my test environment:
Changed name of file from interator.txt to q65771965.txt (suits my environment)
Removed updating of data file so the modifications are shown on-screen.
Replaced REM start with ECHO start to show the start commands on-screen.
Subtle syntax-oriented change : Use set "var1=data" for setting values - this avoids problems caused by trailing spaces.
Significant change : insert a for loop to transfer indirect values to a metavariable (%%a) and use these.
Possibly-required : I don't use setx much, but I've some memory of the argument's needing to be "quoted"

Answer 2

The problem is, you used echo "%acc[!i!]%" within a codeblock. You need another layer of parsing, like call echo "%%acc[!i!]%%"
As an alternative, restructure your code, so the critical part isn't in a code block:
#Echo off
setlocal EnableDelayedExpansion
set acc[0]=default
set acc[1]=Account_2
set acc[2]=Account_3
set acc[3]=Account_4
set acc[4]=Account_5
if not exist interator.txt (
(echo 0)>interator.txt
goto :eof
)
set /p i=<interator.txt
echo "read: !i!"
echo "%acc[!i!]%"
set /A i=i+1
(echo !i!)>interator.txt
echo "write: !i!"
(this code is functionally identically to yours, just structured in another way)
(btw: it should probably iterator, not interator - but that's only spelling)