Cmd - get variable in variable name

Question

I have a problem about variable in variable ( the code is below ) :

set a=1
set b=a
echo %%b%%

The expected result is :

Answer 1

set a=1
set b=a
call echo %%%b%%%

And this will work faster:

@echo off
set a=1
set b=a
setlocal enableDelayedExpansion
echo !%b%!
endlocal

And just in case you need to do this within brackets context (e.g. if , for ...) :

@echo off
set a=1
set b=a
setlocal enableDelayedExpansion
(
 for /f %%v in ("%b%") do echo !%%~v!
)
endlocal