1.例子
echo %time:～0，-1%
显示时间字符，从第0个到最后一个
C:\Documents and Settings>echo %time:~0,-1%
19:00:22.3
C:\Documents and Settings>echo %time%
19:00:29.49
C:\Documents and Settings>echo %date:~2,-1%
12-09-27 星期
C:\Documents and Settings>echo %date:~,3% //第2个参数为正则表示显示的个数，为负则表示显示字符的终点下标
201
C:\Documents and Settings>echo %date:~1,3%
012
2.other
set str=i love you
C:\Documents and Settings>echo %str:~3%
ove you
C:\Documents and Settings>echo %str:~,-1%
i love yo