详细帮助参考：set /? cmd /? 务必仔细看！
具体应用：
1、获取变量子字符串：echo %date:~0,4%%date:~5,2%%date:~-2,2%%time:~0,2%%time:~3,2%%time:~6,2%
2、变量内容替换： set str=000111000 && echo %str:000=222% && echo %date:-=%%time::=%
3、延迟变量环境扩展：cmd /v:on
set /a j=0
for /l %i in (1,1,10) do set /a j=!j!+%i
具体应用：
1、获取变量子字符串：echo %date:~0,4%%date:~5,2%%date:~-2,2%%time:~0,2%%time:~3,2%%time:~6,2%
2、变量内容替换： set str=000111000 && echo %str:000=222% && echo %date:-=%%time::=%
3、延迟变量环境扩展：cmd /v:on
set /a j=0
for /l %i in (1,1,10) do set /a j=!j!+%i
