How to echo a environment variable contains a '&' in DOS batch?

Question

When I type:

set hi=Hello^&World!
echo %hi%

it print Hello and tell me World is not a command

I want it prints Hello&World!

How to do this?

Answer 1

This works for me:

set "hi=Hello^&World!"
echo %hi%

Outputs

Hello&World!

Answer 2

The only secure way to echo the content of a variable is to use the delayed expansion here.
If percent expansion is used, it depends on the content if it fails.

set "var1=Hello ^& World"
set "var2=Hello & World"
setlocal EnableDelayedExpansion
echo !var1!
echo !var2!
echo %var1%
echo %var2% -- fails

The delayed expansion is more usefull as it doesn't interpret any special characters.
More info at SO: How the parser works