lhjoanna

给你两个例子，自己体会下看。以后遇到问题可以先自己写一些辅助代码来查看下问题所在。

@echo off
echo !
echo ^!
setlocal enabledelayedexpansion
echo !
echo ^!
echo ^^!
pause>nul
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@echo off
setlocal enabledelayedexpansion
set str=12345678
echo !str:~-7,1!
echo !str:~-8,1!
echo !str:~-10,1!
echo !str:~-10,1!
echo !str:~-15,1!
echo !str:~-20,1!
echo !str:~-100,1!
echo !str:~-10000,1!
pause>nul
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变量延迟详解
[url=http://www.cn-dos.net/forum/viewthread.php?tid=28273]http://www.cn-dos.net/forum/viewthread.php?tid=28273[/url]

什么情况下该使用变量延迟
http://www.cn-dos.net/forum/viewthread.php?tid=20733

一个变量嵌套变量的问题
http://www.cn-dos.net/forum/viewthread.php?tid=41143

lhjoanna

此例你还是没仔细思考啊，再运行过后看你的这句：
if "!str1:~-%n%,1!" neq "" goto loop
循环能停止吗？

@echo off
setlocal enabledelayedexpansion
set str=12345678
echo !str:~-7,1!
echo !str:~-8,1!
echo !str:~-10,1!
echo !str:~-10,1!
echo !str:~-15,1!
echo !str:~-20,1!
echo !str:~-100,1!
pause>nul
复制代码