问题
I have a small problem with a batch file I'm working on.
Here's a simple sample:
I would like to get the string "THERE" as my result. But the result I get is just "HELLO"
set hello=there
set a=h
set b=ello
set result=%a%%b%
echo %result%
I already tried something like this:
Echo %%result%%
And Sadly, it just gets me the result %HELLO% Any help would be great. Thanks!
回答1:
The reason that %%result%% gives you %result% on the output is that the %% tokens are interpreted first, and further interpretation is not done.
However, you can use that to your advantage, doing a second level of indirection with the following trick:
@echo off
set result=hello
echo %result%
call :iset second %%result%%
echo %second%
goto :eof
:iset
for /F "usebackq tokens=*" %%i in (`echo %%%2%%`) do set %1=%%i
goto :eof
The secret lies in passing the thing you want interpreted (in this case, %%result%% passes in the literal %result% as per the rules stated in the first paragraph, not the interpretation of it).
The for loop then echos the interpretation of that (hello) surrounded by %...% (again, the double %% reduces to %), so that it is also interpreted, and it uses that to set the target variable you also passed in.
The upshot is that it effectively gives you:
%(%result%)%
which is what you're after.
Might I suggest, however, that you start looking into Powershell, so that you don't have to perform these batch-gymnastics in future :-)
来源：https://stackoverflow.com/questions/28578290/batch-how-to-echo-variable