77七

@echo off
set str=" "
setlocal enabledelayedexpansion
if "!str:~-1!" equ " " (
	set "str=!str:~0,-1!"
)
endlocal & set "str=%str%"
rem echo [%str%]
pauseCOPY

提示：如此赋值变量，此时 str的值包括双引号