Question

The article “Passing by Reference” in http://ss64.com/nt/syntax-args.html mentions the following:

In addition to passing numeric or string values on the command line,
it is also possible to pass a variable name and then use the variable
to transfer data between scripts or subroutines.

But how do I do it? When I set the value of a variable and pass it’s name as in

set parm=42
call sub.bat parm

how do I use it in sub.bat?

Answer 1

Via delayed exapansion

@echo off
setlocal
set var1=value1
set var2=value2
call :sub var1
call :sub var2
exit /b

:sub
setlocal enableDelayedExpansion
echo %~1=!%~1!
exit /b

— OUTPUT —

var1=value1
var2=value2