Nested environment variables

Question

I am trying to make a file that asks for your username and password, with a registration. When registering, the passwords are saved in variables.

The problem is i have

Answer 1

You method have an important drawback: How do you know how many different variables are you managing? How do you know that the next user will use user2 variable and the next one user3? You must agree that if there is just one user then password variable don't require the user name and could be named just pass, right?

The standard method to deal with this situation is via an array: you use a variable with same name (the array) and select different values from it via a subscript. In your case, you may have two arrays: user and pass, both with the same numeric subscript starting from 1. For example:

@echo off
setlocal EnableDelayedExpansion
set index=0

:nextUser
set /A index+=1
set /P "user[%index%]=Username: "
set /P "pass[%index%]=Password: "

rem Display data of user[1]:
echo %user[1]%'s password is %pass[1]%

rem Display data of all users, from 1 to %index%
for /L %%i in (1,1,%index%) do (
   echo !user[%%i]!'s password is !pass[%%i]!
)

You may read a detailed description about array management in Batch files at this post: Arrays, linked lists and other data structures in cmd.exe (batch) script

Answer 2

You can use "delayed expansion" to solve the problem of the nested variables. For example, !%user1%pass!: the ! is like % but signals that expansion should be delayed, so %user1% will be expanded first, leaving you with !johnpass! which can be expanded next.

Here's a complete script:

@echo off
setlocal enabledelayedexpansion

set /p "user1=Username: "
set /p "%user1%pass=Password: "

echo %user1%'s password is !%user1%pass!